Make it easier for filesystems to count themselves as jail-enabled,

[FreeBSD/FreeBSD.git] / sys / cddl / contrib / opensolaris / uts / common / fs / zfs / zfs_vfsops.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>.
 * All rights reserved.
 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2016 Nexenta Systems, Inc. All rights reserved.
 */

/* Portions Copyright 2010 Robert Milkowski */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysmacros.h>
#include <sys/kmem.h>
#include <sys/acl.h>
#include <sys/vnode.h>
#include <sys/vfs.h>
#include <sys/mntent.h>
#include <sys/mount.h>
#include <sys/cmn_err.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_dir.h>
#include <sys/zil.h>
#include <sys/fs/zfs.h>
#include <sys/dmu.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_deleg.h>
#include <sys/spa.h>
#include <sys/zap.h>
#include <sys/sa.h>
#include <sys/sa_impl.h>
#include <sys/varargs.h>
#include <sys/policy.h>
#include <sys/atomic.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/sunddi.h>
#include <sys/dnlc.h>
#include <sys/dmu_objset.h>
#include <sys/spa_boot.h>
#include <sys/jail.h>
#include "zfs_comutil.h"

struct mtx zfs_debug_mtx;
MTX_SYSINIT(zfs_debug_mtx, &zfs_debug_mtx, "zfs_debug", MTX_DEF);

SYSCTL_NODE(_vfs, OID_AUTO, zfs, CTLFLAG_RW, 0, "ZFS file system");

int zfs_super_owner;
SYSCTL_INT(_vfs_zfs, OID_AUTO, super_owner, CTLFLAG_RW, &zfs_super_owner, 0,
    "File system owner can perform privileged operation on his file systems");

int zfs_debug_level;
SYSCTL_INT(_vfs_zfs, OID_AUTO, debug, CTLFLAG_RWTUN, &zfs_debug_level, 0,
    "Debug level");

SYSCTL_NODE(_vfs_zfs, OID_AUTO, version, CTLFLAG_RD, 0, "ZFS versions");
static int zfs_version_acl = ZFS_ACL_VERSION;
SYSCTL_INT(_vfs_zfs_version, OID_AUTO, acl, CTLFLAG_RD, &zfs_version_acl, 0,
    "ZFS_ACL_VERSION");
static int zfs_version_spa = SPA_VERSION;
SYSCTL_INT(_vfs_zfs_version, OID_AUTO, spa, CTLFLAG_RD, &zfs_version_spa, 0,
    "SPA_VERSION");
static int zfs_version_zpl = ZPL_VERSION;
SYSCTL_INT(_vfs_zfs_version, OID_AUTO, zpl, CTLFLAG_RD, &zfs_version_zpl, 0,
    "ZPL_VERSION");

static int zfs_mount(vfs_t *vfsp);
static int zfs_umount(vfs_t *vfsp, int fflag);
static int zfs_root(vfs_t *vfsp, int flags, vnode_t **vpp);
static int zfs_statfs(vfs_t *vfsp, struct statfs *statp);
static int zfs_vget(vfs_t *vfsp, ino_t ino, int flags, vnode_t **vpp);
static int zfs_sync(vfs_t *vfsp, int waitfor);
static int zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, int *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int **secflavors);
static int zfs_fhtovp(vfs_t *vfsp, fid_t *fidp, int flags, vnode_t **vpp);
static void zfs_objset_close(zfsvfs_t *zfsvfs);
static void zfs_freevfs(vfs_t *vfsp);

struct vfsops zfs_vfsops = {
        .vfs_mount =            zfs_mount,
        .vfs_unmount =          zfs_umount,
        .vfs_root =             zfs_root,
        .vfs_statfs =           zfs_statfs,
        .vfs_vget =             zfs_vget,
        .vfs_sync =             zfs_sync,
        .vfs_checkexp =         zfs_checkexp,
        .vfs_fhtovp =           zfs_fhtovp,
};

VFS_SET(zfs_vfsops, zfs, VFCF_JAIL | VFCF_DELEGADMIN);

/*
 * We need to keep a count of active fs's.
 * This is necessary to prevent our module
 * from being unloaded after a umount -f
 */
static uint32_t zfs_active_fs_count = 0;

/*ARGSUSED*/
static int
zfs_sync(vfs_t *vfsp, int waitfor)
{

        /*
         * Data integrity is job one.  We don't want a compromised kernel
         * writing to the storage pool, so we never sync during panic.
         */
        if (panicstr)
                return (0);

        /*
         * Ignore the system syncher.  ZFS already commits async data
         * at zfs_txg_timeout intervals.
         */
        if (waitfor == MNT_LAZY)
                return (0);

        if (vfsp != NULL) {
                /*
                 * Sync a specific filesystem.
                 */
                zfsvfs_t *zfsvfs = vfsp->vfs_data;
                dsl_pool_t *dp;
                int error;

                error = vfs_stdsync(vfsp, waitfor);
                if (error != 0)
                        return (error);

                ZFS_ENTER(zfsvfs);
                dp = dmu_objset_pool(zfsvfs->z_os);

                /*
                 * If the system is shutting down, then skip any
                 * filesystems which may exist on a suspended pool.
                 */
                if (sys_shutdown && spa_suspended(dp->dp_spa)) {
                        ZFS_EXIT(zfsvfs);
                        return (0);
                }

                if (zfsvfs->z_log != NULL)
                        zil_commit(zfsvfs->z_log, 0);

                ZFS_EXIT(zfsvfs);
        } else {
                /*
                 * Sync all ZFS filesystems.  This is what happens when you
                 * run sync(1M).  Unlike other filesystems, ZFS honors the
                 * request by waiting for all pools to commit all dirty data.
                 */
                spa_sync_allpools();
        }

        return (0);
}

#ifndef __FreeBSD_kernel__
static int
zfs_create_unique_device(dev_t *dev)
{
        major_t new_major;

        do {
                ASSERT3U(zfs_minor, <=, MAXMIN32);
                minor_t start = zfs_minor;
                do {
                        mutex_enter(&zfs_dev_mtx);
                        if (zfs_minor >= MAXMIN32) {
                                /*
                                 * If we're still using the real major
                                 * keep out of /dev/zfs and /dev/zvol minor
                                 * number space.  If we're using a getudev()'ed
                                 * major number, we can use all of its minors.
                                 */
                                if (zfs_major == ddi_name_to_major(ZFS_DRIVER))
                                        zfs_minor = ZFS_MIN_MINOR;
                                else
                                        zfs_minor = 0;
                        } else {
                                zfs_minor++;
                        }
                        *dev = makedevice(zfs_major, zfs_minor);
                        mutex_exit(&zfs_dev_mtx);
                } while (vfs_devismounted(*dev) && zfs_minor != start);
                if (zfs_minor == start) {
                        /*
                         * We are using all ~262,000 minor numbers for the
                         * current major number.  Create a new major number.
                         */
                        if ((new_major = getudev()) == (major_t)-1) {
                                cmn_err(CE_WARN,
                                    "zfs_mount: Can't get unique major "
                                    "device number.");
                                return (-1);
                        }
                        mutex_enter(&zfs_dev_mtx);
                        zfs_major = new_major;
                        zfs_minor = 0;

                        mutex_exit(&zfs_dev_mtx);
                } else {
                        break;
                }
                /* CONSTANTCONDITION */
        } while (1);

        return (0);
}
#endif  /* !__FreeBSD_kernel__ */

static void
atime_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        if (newval == TRUE) {
                zfsvfs->z_atime = TRUE;
                zfsvfs->z_vfs->vfs_flag &= ~MNT_NOATIME;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NOATIME);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_ATIME, NULL, 0);
        } else {
                zfsvfs->z_atime = FALSE;
                zfsvfs->z_vfs->vfs_flag |= MNT_NOATIME;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_ATIME);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NOATIME, NULL, 0);
        }
}

static void
xattr_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        if (newval == TRUE) {
                /* XXX locking on vfs_flag? */
#ifdef TODO
                zfsvfs->z_vfs->vfs_flag |= VFS_XATTR;
#endif
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NOXATTR);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_XATTR, NULL, 0);
        } else {
                /* XXX locking on vfs_flag? */
#ifdef TODO
                zfsvfs->z_vfs->vfs_flag &= ~VFS_XATTR;
#endif
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_XATTR);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NOXATTR, NULL, 0);
        }
}

static void
blksz_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;
        ASSERT3U(newval, <=, spa_maxblocksize(dmu_objset_spa(zfsvfs->z_os)));
        ASSERT3U(newval, >=, SPA_MINBLOCKSIZE);
        ASSERT(ISP2(newval));

        zfsvfs->z_max_blksz = newval;
        zfsvfs->z_vfs->mnt_stat.f_iosize = newval;
}

static void
readonly_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        if (newval) {
                /* XXX locking on vfs_flag? */
                zfsvfs->z_vfs->vfs_flag |= VFS_RDONLY;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_RW);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_RO, NULL, 0);
        } else {
                /* XXX locking on vfs_flag? */
                zfsvfs->z_vfs->vfs_flag &= ~VFS_RDONLY;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_RO);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_RW, NULL, 0);
        }
}

static void
setuid_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        if (newval == FALSE) {
                zfsvfs->z_vfs->vfs_flag |= VFS_NOSETUID;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_SETUID);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NOSETUID, NULL, 0);
        } else {
                zfsvfs->z_vfs->vfs_flag &= ~VFS_NOSETUID;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NOSETUID);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_SETUID, NULL, 0);
        }
}

static void
exec_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        if (newval == FALSE) {
                zfsvfs->z_vfs->vfs_flag |= VFS_NOEXEC;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_EXEC);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NOEXEC, NULL, 0);
        } else {
                zfsvfs->z_vfs->vfs_flag &= ~VFS_NOEXEC;
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NOEXEC);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_EXEC, NULL, 0);
        }
}

/*
 * The nbmand mount option can be changed at mount time.
 * We can't allow it to be toggled on live file systems or incorrect
 * behavior may be seen from cifs clients
 *
 * This property isn't registered via dsl_prop_register(), but this callback
 * will be called when a file system is first mounted
 */
static void
nbmand_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;
        if (newval == FALSE) {
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NBMAND);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NONBMAND, NULL, 0);
        } else {
                vfs_clearmntopt(zfsvfs->z_vfs, MNTOPT_NONBMAND);
                vfs_setmntopt(zfsvfs->z_vfs, MNTOPT_NBMAND, NULL, 0);
        }
}

static void
snapdir_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        zfsvfs->z_show_ctldir = newval;
}

static void
vscan_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        zfsvfs->z_vscan = newval;
}

static void
acl_mode_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        zfsvfs->z_acl_mode = newval;
}

static void
acl_inherit_changed_cb(void *arg, uint64_t newval)
{
        zfsvfs_t *zfsvfs = arg;

        zfsvfs->z_acl_inherit = newval;
}

static int
zfs_register_callbacks(vfs_t *vfsp)
{
        struct dsl_dataset *ds = NULL;
        objset_t *os = NULL;
        zfsvfs_t *zfsvfs = NULL;
        uint64_t nbmand;
        boolean_t readonly = B_FALSE;
        boolean_t do_readonly = B_FALSE;
        boolean_t setuid = B_FALSE;
        boolean_t do_setuid = B_FALSE;
        boolean_t exec = B_FALSE;
        boolean_t do_exec = B_FALSE;
#ifdef illumos
        boolean_t devices = B_FALSE;
        boolean_t do_devices = B_FALSE;
#endif
        boolean_t xattr = B_FALSE;
        boolean_t do_xattr = B_FALSE;
        boolean_t atime = B_FALSE;
        boolean_t do_atime = B_FALSE;
        int error = 0;

        ASSERT(vfsp);
        zfsvfs = vfsp->vfs_data;
        ASSERT(zfsvfs);
        os = zfsvfs->z_os;

        /*
         * This function can be called for a snapshot when we update snapshot's
         * mount point, which isn't really supported.
         */
        if (dmu_objset_is_snapshot(os))
                return (EOPNOTSUPP);

        /*
         * The act of registering our callbacks will destroy any mount
         * options we may have.  In order to enable temporary overrides
         * of mount options, we stash away the current values and
         * restore them after we register the callbacks.
         */
        if (vfs_optionisset(vfsp, MNTOPT_RO, NULL) ||
            !spa_writeable(dmu_objset_spa(os))) {
                readonly = B_TRUE;
                do_readonly = B_TRUE;
        } else if (vfs_optionisset(vfsp, MNTOPT_RW, NULL)) {
                readonly = B_FALSE;
                do_readonly = B_TRUE;
        }
        if (vfs_optionisset(vfsp, MNTOPT_NOSUID, NULL)) {
                setuid = B_FALSE;
                do_setuid = B_TRUE;
        } else {
                if (vfs_optionisset(vfsp, MNTOPT_NOSETUID, NULL)) {
                        setuid = B_FALSE;
                        do_setuid = B_TRUE;
                } else if (vfs_optionisset(vfsp, MNTOPT_SETUID, NULL)) {
                        setuid = B_TRUE;
                        do_setuid = B_TRUE;
                }
        }
        if (vfs_optionisset(vfsp, MNTOPT_NOEXEC, NULL)) {
                exec = B_FALSE;
                do_exec = B_TRUE;
        } else if (vfs_optionisset(vfsp, MNTOPT_EXEC, NULL)) {
                exec = B_TRUE;
                do_exec = B_TRUE;
        }
        if (vfs_optionisset(vfsp, MNTOPT_NOXATTR, NULL)) {
                xattr = B_FALSE;
                do_xattr = B_TRUE;
        } else if (vfs_optionisset(vfsp, MNTOPT_XATTR, NULL)) {
                xattr = B_TRUE;
                do_xattr = B_TRUE;
        }
        if (vfs_optionisset(vfsp, MNTOPT_NOATIME, NULL)) {
                atime = B_FALSE;
                do_atime = B_TRUE;
        } else if (vfs_optionisset(vfsp, MNTOPT_ATIME, NULL)) {
                atime = B_TRUE;
                do_atime = B_TRUE;
        }

        /*
         * We need to enter pool configuration here, so that we can use
         * dsl_prop_get_int_ds() to handle the special nbmand property below.
         * dsl_prop_get_integer() can not be used, because it has to acquire
         * spa_namespace_lock and we can not do that because we already hold
         * z_teardown_lock.  The problem is that spa_write_cachefile() is called
         * with spa_namespace_lock held and the function calls ZFS vnode
         * operations to write the cache file and thus z_teardown_lock is
         * acquired after spa_namespace_lock.
         */
        ds = dmu_objset_ds(os);
        dsl_pool_config_enter(dmu_objset_pool(os), FTAG);

        /*
         * nbmand is a special property.  It can only be changed at
         * mount time.
         *
         * This is weird, but it is documented to only be changeable
         * at mount time.
         */
        if (vfs_optionisset(vfsp, MNTOPT_NONBMAND, NULL)) {
                nbmand = B_FALSE;
        } else if (vfs_optionisset(vfsp, MNTOPT_NBMAND, NULL)) {
                nbmand = B_TRUE;
        } else if (error = dsl_prop_get_int_ds(ds, "nbmand", &nbmand) != 0) {
                dsl_pool_config_exit(dmu_objset_pool(os), FTAG);
                return (error);
        }

        /*
         * Register property callbacks.
         *
         * It would probably be fine to just check for i/o error from
         * the first prop_register(), but I guess I like to go
         * overboard...
         */
        error = dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ATIME), atime_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_XATTR), xattr_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_RECORDSIZE), blksz_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_READONLY), readonly_changed_cb, zfsvfs);
#ifdef illumos
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_DEVICES), devices_changed_cb, zfsvfs);
#endif
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_SETUID), setuid_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_EXEC), exec_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_SNAPDIR), snapdir_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ACLMODE), acl_mode_changed_cb, zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ACLINHERIT), acl_inherit_changed_cb,
            zfsvfs);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_VSCAN), vscan_changed_cb, zfsvfs);
        dsl_pool_config_exit(dmu_objset_pool(os), FTAG);
        if (error)
                goto unregister;

        /*
         * Invoke our callbacks to restore temporary mount options.
         */
        if (do_readonly)
                readonly_changed_cb(zfsvfs, readonly);
        if (do_setuid)
                setuid_changed_cb(zfsvfs, setuid);
        if (do_exec)
                exec_changed_cb(zfsvfs, exec);
        if (do_xattr)
                xattr_changed_cb(zfsvfs, xattr);
        if (do_atime)
                atime_changed_cb(zfsvfs, atime);

        nbmand_changed_cb(zfsvfs, nbmand);

        return (0);

unregister:
        dsl_prop_unregister_all(ds, zfsvfs);
        return (error);
}

static int
zfs_space_delta_cb(dmu_object_type_t bonustype, void *data,
    uint64_t *userp, uint64_t *groupp)
{
        /*
         * Is it a valid type of object to track?
         */
        if (bonustype != DMU_OT_ZNODE && bonustype != DMU_OT_SA)
                return (SET_ERROR(ENOENT));

        /*
         * If we have a NULL data pointer
         * then assume the id's aren't changing and
         * return EEXIST to the dmu to let it know to
         * use the same ids
         */
        if (data == NULL)
                return (SET_ERROR(EEXIST));

        if (bonustype == DMU_OT_ZNODE) {
                znode_phys_t *znp = data;
                *userp = znp->zp_uid;
                *groupp = znp->zp_gid;
        } else {
                int hdrsize;
                sa_hdr_phys_t *sap = data;
                sa_hdr_phys_t sa = *sap;
                boolean_t swap = B_FALSE;

                ASSERT(bonustype == DMU_OT_SA);

                if (sa.sa_magic == 0) {
                        /*
                         * This should only happen for newly created
                         * files that haven't had the znode data filled
                         * in yet.
                         */
                        *userp = 0;
                        *groupp = 0;
                        return (0);
                }
                if (sa.sa_magic == BSWAP_32(SA_MAGIC)) {
                        sa.sa_magic = SA_MAGIC;
                        sa.sa_layout_info = BSWAP_16(sa.sa_layout_info);
                        swap = B_TRUE;
                } else {
                        VERIFY3U(sa.sa_magic, ==, SA_MAGIC);
                }

                hdrsize = sa_hdrsize(&sa);
                VERIFY3U(hdrsize, >=, sizeof (sa_hdr_phys_t));
                *userp = *((uint64_t *)((uintptr_t)data + hdrsize +
                    SA_UID_OFFSET));
                *groupp = *((uint64_t *)((uintptr_t)data + hdrsize +
                    SA_GID_OFFSET));
                if (swap) {
                        *userp = BSWAP_64(*userp);
                        *groupp = BSWAP_64(*groupp);
                }
        }
        return (0);
}

static void
fuidstr_to_sid(zfsvfs_t *zfsvfs, const char *fuidstr,
    char *domainbuf, int buflen, uid_t *ridp)
{
        uint64_t fuid;
        const char *domain;

        fuid = zfs_strtonum(fuidstr, NULL);

        domain = zfs_fuid_find_by_idx(zfsvfs, FUID_INDEX(fuid));
        if (domain)
                (void) strlcpy(domainbuf, domain, buflen);
        else
                domainbuf[0] = '\0';
        *ridp = FUID_RID(fuid);
}

static uint64_t
zfs_userquota_prop_to_obj(zfsvfs_t *zfsvfs, zfs_userquota_prop_t type)
{
        switch (type) {
        case ZFS_PROP_USERUSED:
                return (DMU_USERUSED_OBJECT);
        case ZFS_PROP_GROUPUSED:
                return (DMU_GROUPUSED_OBJECT);
        case ZFS_PROP_USERQUOTA:
                return (zfsvfs->z_userquota_obj);
        case ZFS_PROP_GROUPQUOTA:
                return (zfsvfs->z_groupquota_obj);
        }
        return (0);
}

int
zfs_userspace_many(zfsvfs_t *zfsvfs, zfs_userquota_prop_t type,
    uint64_t *cookiep, void *vbuf, uint64_t *bufsizep)
{
        int error;
        zap_cursor_t zc;
        zap_attribute_t za;
        zfs_useracct_t *buf = vbuf;
        uint64_t obj;

        if (!dmu_objset_userspace_present(zfsvfs->z_os))
                return (SET_ERROR(ENOTSUP));

        obj = zfs_userquota_prop_to_obj(zfsvfs, type);
        if (obj == 0) {
                *bufsizep = 0;
                return (0);
        }

        for (zap_cursor_init_serialized(&zc, zfsvfs->z_os, obj, *cookiep);
            (error = zap_cursor_retrieve(&zc, &za)) == 0;
            zap_cursor_advance(&zc)) {
                if ((uintptr_t)buf - (uintptr_t)vbuf + sizeof (zfs_useracct_t) >
                    *bufsizep)
                        break;

                fuidstr_to_sid(zfsvfs, za.za_name,
                    buf->zu_domain, sizeof (buf->zu_domain), &buf->zu_rid);

                buf->zu_space = za.za_first_integer;
                buf++;
        }
        if (error == ENOENT)
                error = 0;

        ASSERT3U((uintptr_t)buf - (uintptr_t)vbuf, <=, *bufsizep);
        *bufsizep = (uintptr_t)buf - (uintptr_t)vbuf;
        *cookiep = zap_cursor_serialize(&zc);
        zap_cursor_fini(&zc);
        return (error);
}

/*
 * buf must be big enough (eg, 32 bytes)
 */
static int
id_to_fuidstr(zfsvfs_t *zfsvfs, const char *domain, uid_t rid,
    char *buf, boolean_t addok)
{
        uint64_t fuid;
        int domainid = 0;

        if (domain && domain[0]) {
                domainid = zfs_fuid_find_by_domain(zfsvfs, domain, NULL, addok);
                if (domainid == -1)
                        return (SET_ERROR(ENOENT));
        }
        fuid = FUID_ENCODE(domainid, rid);
        (void) sprintf(buf, "%llx", (longlong_t)fuid);
        return (0);
}

int
zfs_userspace_one(zfsvfs_t *zfsvfs, zfs_userquota_prop_t type,
    const char *domain, uint64_t rid, uint64_t *valp)
{
        char buf[32];
        int err;
        uint64_t obj;

        *valp = 0;

        if (!dmu_objset_userspace_present(zfsvfs->z_os))
                return (SET_ERROR(ENOTSUP));

        obj = zfs_userquota_prop_to_obj(zfsvfs, type);
        if (obj == 0)
                return (0);

        err = id_to_fuidstr(zfsvfs, domain, rid, buf, B_FALSE);
        if (err)
                return (err);

        err = zap_lookup(zfsvfs->z_os, obj, buf, 8, 1, valp);
        if (err == ENOENT)
                err = 0;
        return (err);
}

int
zfs_set_userquota(zfsvfs_t *zfsvfs, zfs_userquota_prop_t type,
    const char *domain, uint64_t rid, uint64_t quota)
{
        char buf[32];
        int err;
        dmu_tx_t *tx;
        uint64_t *objp;
        boolean_t fuid_dirtied;

        if (type != ZFS_PROP_USERQUOTA && type != ZFS_PROP_GROUPQUOTA)
                return (SET_ERROR(EINVAL));

        if (zfsvfs->z_version < ZPL_VERSION_USERSPACE)
                return (SET_ERROR(ENOTSUP));

        objp = (type == ZFS_PROP_USERQUOTA) ? &zfsvfs->z_userquota_obj :
            &zfsvfs->z_groupquota_obj;

        err = id_to_fuidstr(zfsvfs, domain, rid, buf, B_TRUE);
        if (err)
                return (err);
        fuid_dirtied = zfsvfs->z_fuid_dirty;

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, *objp ? *objp : DMU_NEW_OBJECT, B_TRUE, NULL);
        if (*objp == 0) {
                dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_TRUE,
                    zfs_userquota_prop_prefixes[type]);
        }
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err) {
                dmu_tx_abort(tx);
                return (err);
        }

        mutex_enter(&zfsvfs->z_lock);
        if (*objp == 0) {
                *objp = zap_create(zfsvfs->z_os, DMU_OT_USERGROUP_QUOTA,
                    DMU_OT_NONE, 0, tx);
                VERIFY(0 == zap_add(zfsvfs->z_os, MASTER_NODE_OBJ,
                    zfs_userquota_prop_prefixes[type], 8, 1, objp, tx));
        }
        mutex_exit(&zfsvfs->z_lock);

        if (quota == 0) {
                err = zap_remove(zfsvfs->z_os, *objp, buf, tx);
                if (err == ENOENT)
                        err = 0;
        } else {
                err = zap_update(zfsvfs->z_os, *objp, buf, 8, 1, &quota, tx);
        }
        ASSERT(err == 0);
        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);
        dmu_tx_commit(tx);
        return (err);
}

boolean_t
zfs_fuid_overquota(zfsvfs_t *zfsvfs, boolean_t isgroup, uint64_t fuid)
{
        char buf[32];
        uint64_t used, quota, usedobj, quotaobj;
        int err;

        usedobj = isgroup ? DMU_GROUPUSED_OBJECT : DMU_USERUSED_OBJECT;
        quotaobj = isgroup ? zfsvfs->z_groupquota_obj : zfsvfs->z_userquota_obj;

        if (quotaobj == 0 || zfsvfs->z_replay)
                return (B_FALSE);

        (void) sprintf(buf, "%llx", (longlong_t)fuid);
        err = zap_lookup(zfsvfs->z_os, quotaobj, buf, 8, 1, &quota);
        if (err != 0)
                return (B_FALSE);

        err = zap_lookup(zfsvfs->z_os, usedobj, buf, 8, 1, &used);
        if (err != 0)
                return (B_FALSE);
        return (used >= quota);
}

boolean_t
zfs_owner_overquota(zfsvfs_t *zfsvfs, znode_t *zp, boolean_t isgroup)
{
        uint64_t fuid;
        uint64_t quotaobj;

        quotaobj = isgroup ? zfsvfs->z_groupquota_obj : zfsvfs->z_userquota_obj;

        fuid = isgroup ? zp->z_gid : zp->z_uid;

        if (quotaobj == 0 || zfsvfs->z_replay)
                return (B_FALSE);

        return (zfs_fuid_overquota(zfsvfs, isgroup, fuid));
}

/*
 * Associate this zfsvfs with the given objset, which must be owned.
 * This will cache a bunch of on-disk state from the objset in the
 * zfsvfs.
 */
static int
zfsvfs_init(zfsvfs_t *zfsvfs, objset_t *os)
{
        int error;
        uint64_t val;

        zfsvfs->z_max_blksz = SPA_OLD_MAXBLOCKSIZE;
        zfsvfs->z_show_ctldir = ZFS_SNAPDIR_VISIBLE;
        zfsvfs->z_os = os;

        error = zfs_get_zplprop(os, ZFS_PROP_VERSION, &zfsvfs->z_version);
        if (error != 0)
                return (error);
        if (zfsvfs->z_version >
            zfs_zpl_version_map(spa_version(dmu_objset_spa(os)))) {
                (void) printf("Can't mount a version %lld file system "
                    "on a version %lld pool\n. Pool must be upgraded to mount "
                    "this file system.", (u_longlong_t)zfsvfs->z_version,
                    (u_longlong_t)spa_version(dmu_objset_spa(os)));
                return (SET_ERROR(ENOTSUP));
        }
        error = zfs_get_zplprop(os, ZFS_PROP_NORMALIZE, &val);
        if (error != 0)
                return (error);
        zfsvfs->z_norm = (int)val;

        error = zfs_get_zplprop(os, ZFS_PROP_UTF8ONLY, &val);
        if (error != 0)
                return (error);
        zfsvfs->z_utf8 = (val != 0);

        error = zfs_get_zplprop(os, ZFS_PROP_CASE, &val);
        if (error != 0)
                return (error);
        zfsvfs->z_case = (uint_t)val;

        /*
         * Fold case on file systems that are always or sometimes case
         * insensitive.
         */
        if (zfsvfs->z_case == ZFS_CASE_INSENSITIVE ||
            zfsvfs->z_case == ZFS_CASE_MIXED)
                zfsvfs->z_norm |= U8_TEXTPREP_TOUPPER;

        zfsvfs->z_use_fuids = USE_FUIDS(zfsvfs->z_version, zfsvfs->z_os);
        zfsvfs->z_use_sa = USE_SA(zfsvfs->z_version, zfsvfs->z_os);

        uint64_t sa_obj = 0;
        if (zfsvfs->z_use_sa) {
                /* should either have both of these objects or none */
                error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_SA_ATTRS, 8, 1,
                    &sa_obj);
                if (error != 0)
                        return (error);
        }

        error = sa_setup(os, sa_obj, zfs_attr_table, ZPL_END,
            &zfsvfs->z_attr_table);
        if (error != 0)
                return (error);

        if (zfsvfs->z_version >= ZPL_VERSION_SA)
                sa_register_update_callback(os, zfs_sa_upgrade);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_ROOT_OBJ, 8, 1,
            &zfsvfs->z_root);
        if (error != 0)
                return (error);
        ASSERT(zfsvfs->z_root != 0);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_UNLINKED_SET, 8, 1,
            &zfsvfs->z_unlinkedobj);
        if (error != 0)
                return (error);

        error = zap_lookup(os, MASTER_NODE_OBJ,
            zfs_userquota_prop_prefixes[ZFS_PROP_USERQUOTA],
            8, 1, &zfsvfs->z_userquota_obj);
        if (error == ENOENT)
                zfsvfs->z_userquota_obj = 0;
        else if (error != 0)
                return (error);

        error = zap_lookup(os, MASTER_NODE_OBJ,
            zfs_userquota_prop_prefixes[ZFS_PROP_GROUPQUOTA],
            8, 1, &zfsvfs->z_groupquota_obj);
        if (error == ENOENT)
                zfsvfs->z_groupquota_obj = 0;
        else if (error != 0)
                return (error);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_FUID_TABLES, 8, 1,
            &zfsvfs->z_fuid_obj);
        if (error == ENOENT)
                zfsvfs->z_fuid_obj = 0;
        else if (error != 0)
                return (error);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_SHARES_DIR, 8, 1,
            &zfsvfs->z_shares_dir);
        if (error == ENOENT)
                zfsvfs->z_shares_dir = 0;
        else if (error != 0)
                return (error);

        /*
         * Only use the name cache if we are looking for a
         * name on a file system that does not require normalization
         * or case folding.  We can also look there if we happen to be
         * on a non-normalizing, mixed sensitivity file system IF we
         * are looking for the exact name (which is always the case on
         * FreeBSD).
         */
        zfsvfs->z_use_namecache = !zfsvfs->z_norm ||
            ((zfsvfs->z_case == ZFS_CASE_MIXED) &&
            !(zfsvfs->z_norm & ~U8_TEXTPREP_TOUPPER));

        return (0);
}

int
zfsvfs_create(const char *osname, zfsvfs_t **zfvp)
{
        objset_t *os;
        zfsvfs_t *zfsvfs;
        int error;

        /*
         * XXX: Fix struct statfs so this isn't necessary!
         *
         * The 'osname' is used as the filesystem's special node, which means
         * it must fit in statfs.f_mntfromname, or else it can't be
         * enumerated, so libzfs_mnttab_find() returns NULL, which causes
         * 'zfs unmount' to think it's not mounted when it is.
         */
        if (strlen(osname) >= MNAMELEN)
                return (SET_ERROR(ENAMETOOLONG));

        zfsvfs = kmem_zalloc(sizeof (zfsvfs_t), KM_SLEEP);

        /*
         * We claim to always be readonly so we can open snapshots;
         * other ZPL code will prevent us from writing to snapshots.
         */

        error = dmu_objset_own(osname, DMU_OST_ZFS, B_TRUE, zfsvfs, &os);
        if (error != 0) {
                kmem_free(zfsvfs, sizeof (zfsvfs_t));
                return (error);
        }

        error = zfsvfs_create_impl(zfvp, zfsvfs, os);
        if (error != 0) {
                dmu_objset_disown(os, zfsvfs);
        }
        return (error);
}


int
zfsvfs_create_impl(zfsvfs_t **zfvp, zfsvfs_t *zfsvfs, objset_t *os)
{
        int error;

        zfsvfs->z_vfs = NULL;
        zfsvfs->z_parent = zfsvfs;

        mutex_init(&zfsvfs->z_znodes_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&zfsvfs->z_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&zfsvfs->z_all_znodes, sizeof (znode_t),
            offsetof(znode_t, z_link_node));
#ifdef DIAGNOSTIC
        rrm_init(&zfsvfs->z_teardown_lock, B_TRUE);
#else
        rrm_init(&zfsvfs->z_teardown_lock, B_FALSE);
#endif
        rw_init(&zfsvfs->z_teardown_inactive_lock, NULL, RW_DEFAULT, NULL);
        rw_init(&zfsvfs->z_fuid_lock, NULL, RW_DEFAULT, NULL);
        for (int i = 0; i != ZFS_OBJ_MTX_SZ; i++)
                mutex_init(&zfsvfs->z_hold_mtx[i], NULL, MUTEX_DEFAULT, NULL);

        error = zfsvfs_init(zfsvfs, os);
        if (error != 0) {
                *zfvp = NULL;
                kmem_free(zfsvfs, sizeof (zfsvfs_t));
                return (error);
        }

        *zfvp = zfsvfs;
        return (0);
}

static int
zfsvfs_setup(zfsvfs_t *zfsvfs, boolean_t mounting)
{
        int error;

        error = zfs_register_callbacks(zfsvfs->z_vfs);
        if (error)
                return (error);

        zfsvfs->z_log = zil_open(zfsvfs->z_os, zfs_get_data);

        /*
         * If we are not mounting (ie: online recv), then we don't
         * have to worry about replaying the log as we blocked all
         * operations out since we closed the ZIL.
         */
        if (mounting) {
                boolean_t readonly;

                /*
                 * During replay we remove the read only flag to
                 * allow replays to succeed.
                 */
                readonly = zfsvfs->z_vfs->vfs_flag & VFS_RDONLY;
                if (readonly != 0)
                        zfsvfs->z_vfs->vfs_flag &= ~VFS_RDONLY;
                else
                        zfs_unlinked_drain(zfsvfs);

                /*
                 * Parse and replay the intent log.
                 *
                 * Because of ziltest, this must be done after
                 * zfs_unlinked_drain().  (Further note: ziltest
                 * doesn't use readonly mounts, where
                 * zfs_unlinked_drain() isn't called.)  This is because
                 * ziltest causes spa_sync() to think it's committed,
                 * but actually it is not, so the intent log contains
                 * many txg's worth of changes.
                 *
                 * In particular, if object N is in the unlinked set in
                 * the last txg to actually sync, then it could be
                 * actually freed in a later txg and then reallocated
                 * in a yet later txg.  This would write a "create
                 * object N" record to the intent log.  Normally, this
                 * would be fine because the spa_sync() would have
                 * written out the fact that object N is free, before
                 * we could write the "create object N" intent log
                 * record.
                 *
                 * But when we are in ziltest mode, we advance the "open
                 * txg" without actually spa_sync()-ing the changes to
                 * disk.  So we would see that object N is still
                 * allocated and in the unlinked set, and there is an
                 * intent log record saying to allocate it.
                 */
                if (spa_writeable(dmu_objset_spa(zfsvfs->z_os))) {
                        if (zil_replay_disable) {
                                zil_destroy(zfsvfs->z_log, B_FALSE);
                        } else {
                                zfsvfs->z_replay = B_TRUE;
                                zil_replay(zfsvfs->z_os, zfsvfs,
                                    zfs_replay_vector);
                                zfsvfs->z_replay = B_FALSE;
                        }
                }
                zfsvfs->z_vfs->vfs_flag |= readonly; /* restore readonly bit */
        }

        /*
         * Set the objset user_ptr to track its zfsvfs.
         */
        mutex_enter(&zfsvfs->z_os->os_user_ptr_lock);
        dmu_objset_set_user(zfsvfs->z_os, zfsvfs);
        mutex_exit(&zfsvfs->z_os->os_user_ptr_lock);

        return (0);
}

extern krwlock_t zfsvfs_lock; /* in zfs_znode.c */

void
zfsvfs_free(zfsvfs_t *zfsvfs)
{
        int i;

        /*
         * This is a barrier to prevent the filesystem from going away in
         * zfs_znode_move() until we can safely ensure that the filesystem is
         * not unmounted. We consider the filesystem valid before the barrier
         * and invalid after the barrier.
         */
        rw_enter(&zfsvfs_lock, RW_READER);
        rw_exit(&zfsvfs_lock);

        zfs_fuid_destroy(zfsvfs);

        mutex_destroy(&zfsvfs->z_znodes_lock);
        mutex_destroy(&zfsvfs->z_lock);
        list_destroy(&zfsvfs->z_all_znodes);
        rrm_destroy(&zfsvfs->z_teardown_lock);
        rw_destroy(&zfsvfs->z_teardown_inactive_lock);
        rw_destroy(&zfsvfs->z_fuid_lock);
        for (i = 0; i != ZFS_OBJ_MTX_SZ; i++)
                mutex_destroy(&zfsvfs->z_hold_mtx[i]);
        kmem_free(zfsvfs, sizeof (zfsvfs_t));
}

static void
zfs_set_fuid_feature(zfsvfs_t *zfsvfs)
{
        zfsvfs->z_use_fuids = USE_FUIDS(zfsvfs->z_version, zfsvfs->z_os);
        if (zfsvfs->z_vfs) {
                if (zfsvfs->z_use_fuids) {
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_XVATTR);
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_SYSATTR_VIEWS);
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_ACEMASKONACCESS);
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_ACLONCREATE);
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_ACCESS_FILTER);
                        vfs_set_feature(zfsvfs->z_vfs, VFSFT_REPARSE);
                } else {
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_XVATTR);
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_SYSATTR_VIEWS);
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_ACEMASKONACCESS);
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_ACLONCREATE);
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_ACCESS_FILTER);
                        vfs_clear_feature(zfsvfs->z_vfs, VFSFT_REPARSE);
                }
        }
        zfsvfs->z_use_sa = USE_SA(zfsvfs->z_version, zfsvfs->z_os);
}

static int
zfs_domount(vfs_t *vfsp, char *osname)
{
        uint64_t recordsize, fsid_guid;
        int error = 0;
        zfsvfs_t *zfsvfs;
        vnode_t *vp;

        ASSERT(vfsp);
        ASSERT(osname);

        error = zfsvfs_create(osname, &zfsvfs);
        if (error)
                return (error);
        zfsvfs->z_vfs = vfsp;

#ifdef illumos
        /* Initialize the generic filesystem structure. */
        vfsp->vfs_bcount = 0;
        vfsp->vfs_data = NULL;

        if (zfs_create_unique_device(&mount_dev) == -1) {
                error = SET_ERROR(ENODEV);
                goto out;
        }
        ASSERT(vfs_devismounted(mount_dev) == 0);
#endif

        if (error = dsl_prop_get_integer(osname, "recordsize", &recordsize,
            NULL))
                goto out;
        zfsvfs->z_vfs->vfs_bsize = SPA_MINBLOCKSIZE;
        zfsvfs->z_vfs->mnt_stat.f_iosize = recordsize;

        vfsp->vfs_data = zfsvfs;
        vfsp->mnt_flag |= MNT_LOCAL;
        vfsp->mnt_kern_flag |= MNTK_LOOKUP_SHARED;
        vfsp->mnt_kern_flag |= MNTK_SHARED_WRITES;
        vfsp->mnt_kern_flag |= MNTK_EXTENDED_SHARED;
        vfsp->mnt_kern_flag |= MNTK_NO_IOPF;    /* vn_io_fault can be used */

        /*
         * The fsid is 64 bits, composed of an 8-bit fs type, which
         * separates our fsid from any other filesystem types, and a
         * 56-bit objset unique ID.  The objset unique ID is unique to
         * all objsets open on this system, provided by unique_create().
         * The 8-bit fs type must be put in the low bits of fsid[1]
         * because that's where other Solaris filesystems put it.
         */
        fsid_guid = dmu_objset_fsid_guid(zfsvfs->z_os);
        ASSERT((fsid_guid & ~((1ULL<<56)-1)) == 0);
        vfsp->vfs_fsid.val[0] = fsid_guid;
        vfsp->vfs_fsid.val[1] = ((fsid_guid>>32) << 8) |
            vfsp->mnt_vfc->vfc_typenum & 0xFF;

        /*
         * Set features for file system.
         */
        zfs_set_fuid_feature(zfsvfs);
        if (zfsvfs->z_case == ZFS_CASE_INSENSITIVE) {
                vfs_set_feature(vfsp, VFSFT_DIRENTFLAGS);
                vfs_set_feature(vfsp, VFSFT_CASEINSENSITIVE);
                vfs_set_feature(vfsp, VFSFT_NOCASESENSITIVE);
        } else if (zfsvfs->z_case == ZFS_CASE_MIXED) {
                vfs_set_feature(vfsp, VFSFT_DIRENTFLAGS);
                vfs_set_feature(vfsp, VFSFT_CASEINSENSITIVE);
        }
        vfs_set_feature(vfsp, VFSFT_ZEROCOPY_SUPPORTED);

        if (dmu_objset_is_snapshot(zfsvfs->z_os)) {
                uint64_t pval;

                atime_changed_cb(zfsvfs, B_FALSE);
                readonly_changed_cb(zfsvfs, B_TRUE);
                if (error = dsl_prop_get_integer(osname, "xattr", &pval, NULL))
                        goto out;
                xattr_changed_cb(zfsvfs, pval);
                zfsvfs->z_issnap = B_TRUE;
                zfsvfs->z_os->os_sync = ZFS_SYNC_DISABLED;

                mutex_enter(&zfsvfs->z_os->os_user_ptr_lock);
                dmu_objset_set_user(zfsvfs->z_os, zfsvfs);
                mutex_exit(&zfsvfs->z_os->os_user_ptr_lock);
        } else {
                error = zfsvfs_setup(zfsvfs, B_TRUE);
        }

        vfs_mountedfrom(vfsp, osname);

        if (!zfsvfs->z_issnap)
                zfsctl_create(zfsvfs);
out:
        if (error) {
                dmu_objset_disown(zfsvfs->z_os, zfsvfs);
                zfsvfs_free(zfsvfs);
        } else {
                atomic_inc_32(&zfs_active_fs_count);
        }

        return (error);
}

void
zfs_unregister_callbacks(zfsvfs_t *zfsvfs)
{
        objset_t *os = zfsvfs->z_os;

        if (!dmu_objset_is_snapshot(os))
                dsl_prop_unregister_all(dmu_objset_ds(os), zfsvfs);
}

#ifdef SECLABEL
/*
 * Convert a decimal digit string to a uint64_t integer.
 */
static int
str_to_uint64(char *str, uint64_t *objnum)
{
        uint64_t num = 0;

        while (*str) {
                if (*str < '0' || *str > '9')
                        return (SET_ERROR(EINVAL));

                num = num*10 + *str++ - '0';
        }

        *objnum = num;
        return (0);
}

/*
 * The boot path passed from the boot loader is in the form of
 * "rootpool-name/root-filesystem-object-number'. Convert this
 * string to a dataset name: "rootpool-name/root-filesystem-name".
 */
static int
zfs_parse_bootfs(char *bpath, char *outpath)
{
        char *slashp;
        uint64_t objnum;
        int error;

        if (*bpath == 0 || *bpath == '/')
                return (SET_ERROR(EINVAL));

        (void) strcpy(outpath, bpath);

        slashp = strchr(bpath, '/');

        /* if no '/', just return the pool name */
        if (slashp == NULL) {
                return (0);
        }

        /* if not a number, just return the root dataset name */
        if (str_to_uint64(slashp+1, &objnum)) {
                return (0);
        }

        *slashp = '\0';
        error = dsl_dsobj_to_dsname(bpath, objnum, outpath);
        *slashp = '/';

        return (error);
}

/*
 * Check that the hex label string is appropriate for the dataset being
 * mounted into the global_zone proper.
 *
 * Return an error if the hex label string is not default or
 * admin_low/admin_high.  For admin_low labels, the corresponding
 * dataset must be readonly.
 */
int
zfs_check_global_label(const char *dsname, const char *hexsl)
{
        if (strcasecmp(hexsl, ZFS_MLSLABEL_DEFAULT) == 0)
                return (0);
        if (strcasecmp(hexsl, ADMIN_HIGH) == 0)
                return (0);
        if (strcasecmp(hexsl, ADMIN_LOW) == 0) {
                /* must be readonly */
                uint64_t rdonly;

                if (dsl_prop_get_integer(dsname,
                    zfs_prop_to_name(ZFS_PROP_READONLY), &rdonly, NULL))
                        return (SET_ERROR(EACCES));
                return (rdonly ? 0 : EACCES);
        }
        return (SET_ERROR(EACCES));
}

/*
 * Determine whether the mount is allowed according to MAC check.
 * by comparing (where appropriate) label of the dataset against
 * the label of the zone being mounted into.  If the dataset has
 * no label, create one.
 *
 * Returns 0 if access allowed, error otherwise (e.g. EACCES)
 */
static int
zfs_mount_label_policy(vfs_t *vfsp, char *osname)
{
        int             error, retv;
        zone_t          *mntzone = NULL;
        ts_label_t      *mnt_tsl;
        bslabel_t       *mnt_sl;
        bslabel_t       ds_sl;
        char            ds_hexsl[MAXNAMELEN];

        retv = EACCES;                          /* assume the worst */

        /*
         * Start by getting the dataset label if it exists.
         */
        error = dsl_prop_get(osname, zfs_prop_to_name(ZFS_PROP_MLSLABEL),
            1, sizeof (ds_hexsl), &ds_hexsl, NULL);
        if (error)
                return (SET_ERROR(EACCES));

        /*
         * If labeling is NOT enabled, then disallow the mount of datasets
         * which have a non-default label already.  No other label checks
         * are needed.
         */
        if (!is_system_labeled()) {
                if (strcasecmp(ds_hexsl, ZFS_MLSLABEL_DEFAULT) == 0)
                        return (0);
                return (SET_ERROR(EACCES));
        }

        /*
         * Get the label of the mountpoint.  If mounting into the global
         * zone (i.e. mountpoint is not within an active zone and the
         * zoned property is off), the label must be default or
         * admin_low/admin_high only; no other checks are needed.
         */
        mntzone = zone_find_by_any_path(refstr_value(vfsp->vfs_mntpt), B_FALSE);
        if (mntzone->zone_id == GLOBAL_ZONEID) {
                uint64_t zoned;

                zone_rele(mntzone);

                if (dsl_prop_get_integer(osname,
                    zfs_prop_to_name(ZFS_PROP_ZONED), &zoned, NULL))
                        return (SET_ERROR(EACCES));
                if (!zoned)
                        return (zfs_check_global_label(osname, ds_hexsl));
                else
                        /*
                         * This is the case of a zone dataset being mounted
                         * initially, before the zone has been fully created;
                         * allow this mount into global zone.
                         */
                        return (0);
        }

        mnt_tsl = mntzone->zone_slabel;
        ASSERT(mnt_tsl != NULL);
        label_hold(mnt_tsl);
        mnt_sl = label2bslabel(mnt_tsl);

        if (strcasecmp(ds_hexsl, ZFS_MLSLABEL_DEFAULT) == 0) {
                /*
                 * The dataset doesn't have a real label, so fabricate one.
                 */
                char *str = NULL;

                if (l_to_str_internal(mnt_sl, &str) == 0 &&
                    dsl_prop_set_string(osname,
                    zfs_prop_to_name(ZFS_PROP_MLSLABEL),
                    ZPROP_SRC_LOCAL, str) == 0)
                        retv = 0;
                if (str != NULL)
                        kmem_free(str, strlen(str) + 1);
        } else if (hexstr_to_label(ds_hexsl, &ds_sl) == 0) {
                /*
                 * Now compare labels to complete the MAC check.  If the
                 * labels are equal then allow access.  If the mountpoint
                 * label dominates the dataset label, allow readonly access.
                 * Otherwise, access is denied.
                 */
                if (blequal(mnt_sl, &ds_sl))
                        retv = 0;
                else if (bldominates(mnt_sl, &ds_sl)) {
                        vfs_setmntopt(vfsp, MNTOPT_RO, NULL, 0);
                        retv = 0;
                }
        }

        label_rele(mnt_tsl);
        zone_rele(mntzone);
        return (retv);
}
#endif  /* SECLABEL */

#ifdef OPENSOLARIS_MOUNTROOT
static int
zfs_mountroot(vfs_t *vfsp, enum whymountroot why)
{
        int error = 0;
        static int zfsrootdone = 0;
        zfsvfs_t *zfsvfs = NULL;
        znode_t *zp = NULL;
        vnode_t *vp = NULL;
        char *zfs_bootfs;
        char *zfs_devid;

        ASSERT(vfsp);

        /*
         * The filesystem that we mount as root is defined in the
         * boot property "zfs-bootfs" with a format of
         * "poolname/root-dataset-objnum".
         */
        if (why == ROOT_INIT) {
                if (zfsrootdone++)
                        return (SET_ERROR(EBUSY));
                /*
                 * the process of doing a spa_load will require the
                 * clock to be set before we could (for example) do
                 * something better by looking at the timestamp on
                 * an uberblock, so just set it to -1.
                 */
                clkset(-1);

                if ((zfs_bootfs = spa_get_bootprop("zfs-bootfs")) == NULL) {
                        cmn_err(CE_NOTE, "spa_get_bootfs: can not get "
                            "bootfs name");
                        return (SET_ERROR(EINVAL));
                }
                zfs_devid = spa_get_bootprop("diskdevid");
                error = spa_import_rootpool(rootfs.bo_name, zfs_devid);
                if (zfs_devid)
                        spa_free_bootprop(zfs_devid);
                if (error) {
                        spa_free_bootprop(zfs_bootfs);
                        cmn_err(CE_NOTE, "spa_import_rootpool: error %d",
                            error);
                        return (error);
                }
                if (error = zfs_parse_bootfs(zfs_bootfs, rootfs.bo_name)) {
                        spa_free_bootprop(zfs_bootfs);
                        cmn_err(CE_NOTE, "zfs_parse_bootfs: error %d",
                            error);
                        return (error);
                }

                spa_free_bootprop(zfs_bootfs);

                if (error = vfs_lock(vfsp))
                        return (error);

                if (error = zfs_domount(vfsp, rootfs.bo_name)) {
                        cmn_err(CE_NOTE, "zfs_domount: error %d", error);
                        goto out;
                }

                zfsvfs = (zfsvfs_t *)vfsp->vfs_data;
                ASSERT(zfsvfs);
                if (error = zfs_zget(zfsvfs, zfsvfs->z_root, &zp)) {
                        cmn_err(CE_NOTE, "zfs_zget: error %d", error);
                        goto out;
                }

                vp = ZTOV(zp);
                mutex_enter(&vp->v_lock);
                vp->v_flag |= VROOT;
                mutex_exit(&vp->v_lock);
                rootvp = vp;

                /*
                 * Leave rootvp held.  The root file system is never unmounted.
                 */

                vfs_add((struct vnode *)0, vfsp,
                    (vfsp->vfs_flag & VFS_RDONLY) ? MS_RDONLY : 0);
out:
                vfs_unlock(vfsp);
                return (error);
        } else if (why == ROOT_REMOUNT) {
                readonly_changed_cb(vfsp->vfs_data, B_FALSE);
                vfsp->vfs_flag |= VFS_REMOUNT;

                /* refresh mount options */
                zfs_unregister_callbacks(vfsp->vfs_data);
                return (zfs_register_callbacks(vfsp));

        } else if (why == ROOT_UNMOUNT) {
                zfs_unregister_callbacks((zfsvfs_t *)vfsp->vfs_data);
                (void) zfs_sync(vfsp, 0, 0);
                return (0);
        }

        /*
         * if "why" is equal to anything else other than ROOT_INIT,
         * ROOT_REMOUNT, or ROOT_UNMOUNT, we do not support it.
         */
        return (SET_ERROR(ENOTSUP));
}
#endif  /* OPENSOLARIS_MOUNTROOT */

static int
getpoolname(const char *osname, char *poolname)
{
        char *p;

        p = strchr(osname, '/');
        if (p == NULL) {
                if (strlen(osname) >= MAXNAMELEN)
                        return (ENAMETOOLONG);
                (void) strcpy(poolname, osname);
        } else {
                if (p - osname >= MAXNAMELEN)
                        return (ENAMETOOLONG);
                (void) strncpy(poolname, osname, p - osname);
                poolname[p - osname] = '\0';
        }
        return (0);
}

/*ARGSUSED*/
static int
zfs_mount(vfs_t *vfsp)
{
        kthread_t       *td = curthread;
        vnode_t         *mvp = vfsp->mnt_vnodecovered;
        cred_t          *cr = td->td_ucred;
        char            *osname;
        int             error = 0;
        int             canwrite;

#ifdef illumos
        if (mvp->v_type != VDIR)
                return (SET_ERROR(ENOTDIR));

        mutex_enter(&mvp->v_lock);
        if ((uap->flags & MS_REMOUNT) == 0 &&
            (uap->flags & MS_OVERLAY) == 0 &&
            (mvp->v_count != 1 || (mvp->v_flag & VROOT))) {
                mutex_exit(&mvp->v_lock);
                return (SET_ERROR(EBUSY));
        }
        mutex_exit(&mvp->v_lock);

        /*
         * ZFS does not support passing unparsed data in via MS_DATA.
         * Users should use the MS_OPTIONSTR interface; this means
         * that all option parsing is already done and the options struct
         * can be interrogated.
         */
        if ((uap->flags & MS_DATA) && uap->datalen > 0)
                return (SET_ERROR(EINVAL));

        /*
         * Get the objset name (the "special" mount argument).
         */
        if (error = pn_get(uap->spec, fromspace, &spn))
                return (error);

        osname = spn.pn_path;
#else   /* !illumos */
        if (vfs_getopt(vfsp->mnt_optnew, "from", (void **)&osname, NULL))
                return (SET_ERROR(EINVAL));

        /*
         * If full-owner-access is enabled and delegated administration is
         * turned on, we must set nosuid.
         */
        if (zfs_super_owner &&
            dsl_deleg_access(osname, ZFS_DELEG_PERM_MOUNT, cr) != ECANCELED) {
                secpolicy_fs_mount_clearopts(cr, vfsp);
        }
#endif  /* illumos */

        /*
         * Check for mount privilege?
         *
         * If we don't have privilege then see if
         * we have local permission to allow it
         */
        error = secpolicy_fs_mount(cr, mvp, vfsp);
        if (error) {
                if (dsl_deleg_access(osname, ZFS_DELEG_PERM_MOUNT, cr) != 0)
                        goto out;

                if (!(vfsp->vfs_flag & MS_REMOUNT)) {
                        vattr_t         vattr;

                        /*
                         * Make sure user is the owner of the mount point
                         * or has sufficient privileges.
                         */

                        vattr.va_mask = AT_UID;

                        vn_lock(mvp, LK_SHARED | LK_RETRY);
                        if (VOP_GETATTR(mvp, &vattr, cr)) {
                                VOP_UNLOCK(mvp, 0);
                                goto out;
                        }

                        if (secpolicy_vnode_owner(mvp, cr, vattr.va_uid) != 0 &&
                            VOP_ACCESS(mvp, VWRITE, cr, td) != 0) {
                                VOP_UNLOCK(mvp, 0);
                                goto out;
                        }
                        VOP_UNLOCK(mvp, 0);
                }

                secpolicy_fs_mount_clearopts(cr, vfsp);
        }

        /*
         * Refuse to mount a filesystem if we are in a local zone and the
         * dataset is not visible.
         */
        if (!INGLOBALZONE(curthread) &&
            (!zone_dataset_visible(osname, &canwrite) || !canwrite)) {
                error = SET_ERROR(EPERM);
                goto out;
        }

#ifdef SECLABEL
        error = zfs_mount_label_policy(vfsp, osname);
        if (error)
                goto out;
#endif

        vfsp->vfs_flag |= MNT_NFS4ACLS;

        /*
         * When doing a remount, we simply refresh our temporary properties
         * according to those options set in the current VFS options.
         */
        if (vfsp->vfs_flag & MS_REMOUNT) {
                zfsvfs_t *zfsvfs = vfsp->vfs_data;

                /*
                 * Refresh mount options with z_teardown_lock blocking I/O while
                 * the filesystem is in an inconsistent state.
                 * The lock also serializes this code with filesystem
                 * manipulations between entry to zfs_suspend_fs() and return
                 * from zfs_resume_fs().
                 */
                rrm_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG);
                zfs_unregister_callbacks(zfsvfs);
                error = zfs_register_callbacks(vfsp);
                rrm_exit(&zfsvfs->z_teardown_lock, FTAG);
                goto out;
        }

        /* Initial root mount: try hard to import the requested root pool. */
        if ((vfsp->vfs_flag & MNT_ROOTFS) != 0 &&
            (vfsp->vfs_flag & MNT_UPDATE) == 0) {
                char pname[MAXNAMELEN];

                error = getpoolname(osname, pname);
                if (error == 0)
                        error = spa_import_rootpool(pname);
                if (error)
                        goto out;
        }
        DROP_GIANT();
        error = zfs_domount(vfsp, osname);
        PICKUP_GIANT();

#ifdef illumos
        /*
         * Add an extra VFS_HOLD on our parent vfs so that it can't
         * disappear due to a forced unmount.
         */
        if (error == 0 && ((zfsvfs_t *)vfsp->vfs_data)->z_issnap)
                VFS_HOLD(mvp->v_vfsp);
#endif

out:
        return (error);
}

static int
zfs_statfs(vfs_t *vfsp, struct statfs *statp)
{
        zfsvfs_t *zfsvfs = vfsp->vfs_data;
        uint64_t refdbytes, availbytes, usedobjs, availobjs;

        statp->f_version = STATFS_VERSION;

        ZFS_ENTER(zfsvfs);

        dmu_objset_space(zfsvfs->z_os,
            &refdbytes, &availbytes, &usedobjs, &availobjs);

        /*
         * The underlying storage pool actually uses multiple block sizes.
         * We report the fragsize as the smallest block size we support,
         * and we report our blocksize as the filesystem's maximum blocksize.
         */
        statp->f_bsize = SPA_MINBLOCKSIZE;
        statp->f_iosize = zfsvfs->z_vfs->mnt_stat.f_iosize;

        /*
         * The following report "total" blocks of various kinds in the
         * file system, but reported in terms of f_frsize - the
         * "fragment" size.
         */

        statp->f_blocks = (refdbytes + availbytes) >> SPA_MINBLOCKSHIFT;
        statp->f_bfree = availbytes / statp->f_bsize;
        statp->f_bavail = statp->f_bfree; /* no root reservation */

        /*
         * statvfs() should really be called statufs(), because it assumes
         * static metadata.  ZFS doesn't preallocate files, so the best
         * we can do is report the max that could possibly fit in f_files,
         * and that minus the number actually used in f_ffree.
         * For f_ffree, report the smaller of the number of object available
         * and the number of blocks (each object will take at least a block).
         */
        statp->f_ffree = MIN(availobjs, statp->f_bfree);
        statp->f_files = statp->f_ffree + usedobjs;

        /*
         * We're a zfs filesystem.
         */
        (void) strlcpy(statp->f_fstypename, "zfs", sizeof(statp->f_fstypename));

        strlcpy(statp->f_mntfromname, vfsp->mnt_stat.f_mntfromname,
            sizeof(statp->f_mntfromname));
        strlcpy(statp->f_mntonname, vfsp->mnt_stat.f_mntonname,
            sizeof(statp->f_mntonname));

        statp->f_namemax = MAXNAMELEN - 1;

        ZFS_EXIT(zfsvfs);
        return (0);
}

static int
zfs_root(vfs_t *vfsp, int flags, vnode_t **vpp)
{
        zfsvfs_t *zfsvfs = vfsp->vfs_data;
        znode_t *rootzp;
        int error;

        ZFS_ENTER(zfsvfs);

        error = zfs_zget(zfsvfs, zfsvfs->z_root, &rootzp);
        if (error == 0)
                *vpp = ZTOV(rootzp);

        ZFS_EXIT(zfsvfs);

        if (error == 0) {
                error = vn_lock(*vpp, flags);
                if (error != 0) {
                        VN_RELE(*vpp);
                        *vpp = NULL;
                }
        }
        return (error);
}

/*
 * Teardown the zfsvfs::z_os.
 *
 * Note, if 'unmounting' is FALSE, we return with the 'z_teardown_lock'
 * and 'z_teardown_inactive_lock' held.
 */
static int
zfsvfs_teardown(zfsvfs_t *zfsvfs, boolean_t unmounting)
{
        znode_t *zp;

        rrm_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG);

        if (!unmounting) {
                /*
                 * We purge the parent filesystem's vfsp as the parent
                 * filesystem and all of its snapshots have their vnode's
                 * v_vfsp set to the parent's filesystem's vfsp.  Note,
                 * 'z_parent' is self referential for non-snapshots.
                 */
                (void) dnlc_purge_vfsp(zfsvfs->z_parent->z_vfs, 0);
#ifdef FREEBSD_NAMECACHE
                cache_purgevfs(zfsvfs->z_parent->z_vfs, true);
#endif
        }

        /*
         * Close the zil. NB: Can't close the zil while zfs_inactive
         * threads are blocked as zil_close can call zfs_inactive.
         */
        if (zfsvfs->z_log) {
                zil_close(zfsvfs->z_log);
                zfsvfs->z_log = NULL;
        }

        rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_WRITER);

        /*
         * If we are not unmounting (ie: online recv) and someone already
         * unmounted this file system while we were doing the switcheroo,
         * or a reopen of z_os failed then just bail out now.
         */
        if (!unmounting && (zfsvfs->z_unmounted || zfsvfs->z_os == NULL)) {
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
                rrm_exit(&zfsvfs->z_teardown_lock, FTAG);
                return (SET_ERROR(EIO));
        }

        /*
         * At this point there are no vops active, and any new vops will
         * fail with EIO since we have z_teardown_lock for writer (only
         * relavent for forced unmount).
         *
         * Release all holds on dbufs.
         */
        mutex_enter(&zfsvfs->z_znodes_lock);
        for (zp = list_head(&zfsvfs->z_all_znodes); zp != NULL;
            zp = list_next(&zfsvfs->z_all_znodes, zp))
                if (zp->z_sa_hdl) {
                        ASSERT(ZTOV(zp)->v_count >= 0);
                        zfs_znode_dmu_fini(zp);
                }
        mutex_exit(&zfsvfs->z_znodes_lock);

        /*
         * If we are unmounting, set the unmounted flag and let new vops
         * unblock.  zfs_inactive will have the unmounted behavior, and all
         * other vops will fail with EIO.
         */
        if (unmounting) {
                zfsvfs->z_unmounted = B_TRUE;
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
                rrm_exit(&zfsvfs->z_teardown_lock, FTAG);
        }

        /*
         * z_os will be NULL if there was an error in attempting to reopen
         * zfsvfs, so just return as the properties had already been
         * unregistered and cached data had been evicted before.
         */
        if (zfsvfs->z_os == NULL)
                return (0);

        /*
         * Unregister properties.
         */
        zfs_unregister_callbacks(zfsvfs);

        /*
         * Evict cached data
         */
        if (dsl_dataset_is_dirty(dmu_objset_ds(zfsvfs->z_os)) &&
            !(zfsvfs->z_vfs->vfs_flag & VFS_RDONLY))
                txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), 0);
        dmu_objset_evict_dbufs(zfsvfs->z_os);

        return (0);
}

/*ARGSUSED*/
static int
zfs_umount(vfs_t *vfsp, int fflag)
{
        kthread_t *td = curthread;
        zfsvfs_t *zfsvfs = vfsp->vfs_data;
        objset_t *os;
        cred_t *cr = td->td_ucred;
        int ret;

        ret = secpolicy_fs_unmount(cr, vfsp);
        if (ret) {
                if (dsl_deleg_access((char *)refstr_value(vfsp->vfs_resource),
                    ZFS_DELEG_PERM_MOUNT, cr))
                        return (ret);
        }

        /*
         * We purge the parent filesystem's vfsp as the parent filesystem
         * and all of its snapshots have their vnode's v_vfsp set to the
         * parent's filesystem's vfsp.  Note, 'z_parent' is self
         * referential for non-snapshots.
         */
        (void) dnlc_purge_vfsp(zfsvfs->z_parent->z_vfs, 0);

        /*
         * Unmount any snapshots mounted under .zfs before unmounting the
         * dataset itself.
         */
        if (zfsvfs->z_ctldir != NULL) {
                if ((ret = zfsctl_umount_snapshots(vfsp, fflag, cr)) != 0)
                        return (ret);
        }

        if (fflag & MS_FORCE) {
                /*
                 * Mark file system as unmounted before calling
                 * vflush(FORCECLOSE). This way we ensure no future vnops
                 * will be called and risk operating on DOOMED vnodes.
                 */
                rrm_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG);
                zfsvfs->z_unmounted = B_TRUE;
                rrm_exit(&zfsvfs->z_teardown_lock, FTAG);
        }

        /*
         * Flush all the files.
         */
        ret = vflush(vfsp, 0, (fflag & MS_FORCE) ? FORCECLOSE : 0, td);
        if (ret != 0)
                return (ret);

#ifdef illumos
        if (!(fflag & MS_FORCE)) {
                /*
                 * Check the number of active vnodes in the file system.
                 * Our count is maintained in the vfs structure, but the
                 * number is off by 1 to indicate a hold on the vfs
                 * structure itself.
                 *
                 * The '.zfs' directory maintains a reference of its
                 * own, and any active references underneath are
                 * reflected in the vnode count.
                 */
                if (zfsvfs->z_ctldir == NULL) {
                        if (vfsp->vfs_count > 1)
                                return (SET_ERROR(EBUSY));
                } else {
                        if (vfsp->vfs_count > 2 ||
                            zfsvfs->z_ctldir->v_count > 1)
                                return (SET_ERROR(EBUSY));
                }
        }
#endif

        VERIFY(zfsvfs_teardown(zfsvfs, B_TRUE) == 0);
        os = zfsvfs->z_os;

        /*
         * z_os will be NULL if there was an error in
         * attempting to reopen zfsvfs.
         */
        if (os != NULL) {
                /*
                 * Unset the objset user_ptr.
                 */
                mutex_enter(&os->os_user_ptr_lock);
                dmu_objset_set_user(os, NULL);
                mutex_exit(&os->os_user_ptr_lock);

                /*
                 * Finally release the objset
                 */
                dmu_objset_disown(os, zfsvfs);
        }

        /*
         * We can now safely destroy the '.zfs' directory node.
         */
        if (zfsvfs->z_ctldir != NULL)
                zfsctl_destroy(zfsvfs);
        zfs_freevfs(vfsp);

        return (0);
}

static int
zfs_vget(vfs_t *vfsp, ino_t ino, int flags, vnode_t **vpp)
{
        zfsvfs_t        *zfsvfs = vfsp->vfs_data;
        znode_t         *zp;
        int             err;

        /*
         * zfs_zget() can't operate on virtual entries like .zfs/ or
         * .zfs/snapshot/ directories, that's why we return EOPNOTSUPP.
         * This will make NFS to switch to LOOKUP instead of using VGET.
         */
        if (ino == ZFSCTL_INO_ROOT || ino == ZFSCTL_INO_SNAPDIR ||
            (zfsvfs->z_shares_dir != 0 && ino == zfsvfs->z_shares_dir))
                return (EOPNOTSUPP);

        ZFS_ENTER(zfsvfs);
        err = zfs_zget(zfsvfs, ino, &zp);
        if (err == 0 && zp->z_unlinked) {
                vrele(ZTOV(zp));
                err = EINVAL;
        }
        if (err == 0)
                *vpp = ZTOV(zp);
        ZFS_EXIT(zfsvfs);
        if (err == 0)
                err = vn_lock(*vpp, flags);
        if (err != 0)
                *vpp = NULL;
        return (err);
}

static int
zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, int *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int **secflavors)
{
        zfsvfs_t *zfsvfs = vfsp->vfs_data;

        /*
         * If this is regular file system vfsp is the same as
         * zfsvfs->z_parent->z_vfs, but if it is snapshot,
         * zfsvfs->z_parent->z_vfs represents parent file system
         * which we have to use here, because only this file system
         * has mnt_export configured.
         */
        return (vfs_stdcheckexp(zfsvfs->z_parent->z_vfs, nam, extflagsp,
            credanonp, numsecflavors, secflavors));
}

CTASSERT(SHORT_FID_LEN <= sizeof(struct fid));
CTASSERT(LONG_FID_LEN <= sizeof(struct fid));

static int
zfs_fhtovp(vfs_t *vfsp, fid_t *fidp, int flags, vnode_t **vpp)
{
        struct componentname cn;
        zfsvfs_t        *zfsvfs = vfsp->vfs_data;
        znode_t         *zp;
        vnode_t         *dvp;
        uint64_t        object = 0;
        uint64_t        fid_gen = 0;
        uint64_t        gen_mask;
        uint64_t        zp_gen;
        int             i, err;

        *vpp = NULL;

        ZFS_ENTER(zfsvfs);

        /*
         * On FreeBSD we can get snapshot's mount point or its parent file
         * system mount point depending if snapshot is already mounted or not.
         */
        if (zfsvfs->z_parent == zfsvfs && fidp->fid_len == LONG_FID_LEN) {
                zfid_long_t     *zlfid = (zfid_long_t *)fidp;
                uint64_t        objsetid = 0;
                uint64_t        setgen = 0;

                for (i = 0; i < sizeof (zlfid->zf_setid); i++)
                        objsetid |= ((uint64_t)zlfid->zf_setid[i]) << (8 * i);

                for (i = 0; i < sizeof (zlfid->zf_setgen); i++)
                        setgen |= ((uint64_t)zlfid->zf_setgen[i]) << (8 * i);

                ZFS_EXIT(zfsvfs);

                err = zfsctl_lookup_objset(vfsp, objsetid, &zfsvfs);
                if (err)
                        return (SET_ERROR(EINVAL));
                ZFS_ENTER(zfsvfs);
        }

        if (fidp->fid_len == SHORT_FID_LEN || fidp->fid_len == LONG_FID_LEN) {
                zfid_short_t    *zfid = (zfid_short_t *)fidp;

                for (i = 0; i < sizeof (zfid->zf_object); i++)
                        object |= ((uint64_t)zfid->zf_object[i]) << (8 * i);

                for (i = 0; i < sizeof (zfid->zf_gen); i++)
                        fid_gen |= ((uint64_t)zfid->zf_gen[i]) << (8 * i);
        } else {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EINVAL));
        }

        /*
         * A zero fid_gen means we are in .zfs or the .zfs/snapshot
         * directory tree. If the object == zfsvfs->z_shares_dir, then
         * we are in the .zfs/shares directory tree.
         */
        if ((fid_gen == 0 &&
             (object == ZFSCTL_INO_ROOT || object == ZFSCTL_INO_SNAPDIR)) ||
            (zfsvfs->z_shares_dir != 0 && object == zfsvfs->z_shares_dir)) {
                ZFS_EXIT(zfsvfs);
                VERIFY0(zfsctl_root(zfsvfs, LK_SHARED, &dvp));
                if (object == ZFSCTL_INO_SNAPDIR) {
                        cn.cn_nameptr = "snapshot";
                        cn.cn_namelen = strlen(cn.cn_nameptr);
                        cn.cn_nameiop = LOOKUP;
                        cn.cn_flags = ISLASTCN | LOCKLEAF;
                        cn.cn_lkflags = flags;
                        VERIFY0(VOP_LOOKUP(dvp, vpp, &cn));
                        vput(dvp);
                } else if (object == zfsvfs->z_shares_dir) {
                        /*
                         * XXX This branch must not be taken,
                         * if it is, then the lookup below will
                         * explode.
                         */
                        cn.cn_nameptr = "shares";
                        cn.cn_namelen = strlen(cn.cn_nameptr);
                        cn.cn_nameiop = LOOKUP;
                        cn.cn_flags = ISLASTCN;
                        cn.cn_lkflags = flags;
                        VERIFY0(VOP_LOOKUP(dvp, vpp, &cn));
                        vput(dvp);
                } else {
                        *vpp = dvp;
                }
                return (err);
        }

        gen_mask = -1ULL >> (64 - 8 * i);

        dprintf("getting %llu [%u mask %llx]\n", object, fid_gen, gen_mask);
        if (err = zfs_zget(zfsvfs, object, &zp)) {
                ZFS_EXIT(zfsvfs);
                return (err);
        }
        (void) sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(zfsvfs), &zp_gen,
            sizeof (uint64_t));
        zp_gen = zp_gen & gen_mask;
        if (zp_gen == 0)
                zp_gen = 1;
        if (zp->z_unlinked || zp_gen != fid_gen) {
                dprintf("znode gen (%u) != fid gen (%u)\n", zp_gen, fid_gen);
                vrele(ZTOV(zp));
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EINVAL));
        }

        *vpp = ZTOV(zp);
        ZFS_EXIT(zfsvfs);
        err = vn_lock(*vpp, flags);
        if (err == 0)
                vnode_create_vobject(*vpp, zp->z_size, curthread);
        else
                *vpp = NULL;
        return (err);
}

/*
 * Block out VOPs and close zfsvfs_t::z_os
 *
 * Note, if successful, then we return with the 'z_teardown_lock' and
 * 'z_teardown_inactive_lock' write held.  We leave ownership of the underlying
 * dataset and objset intact so that they can be atomically handed off during
 * a subsequent rollback or recv operation and the resume thereafter.
 */
int
zfs_suspend_fs(zfsvfs_t *zfsvfs)
{
        int error;

        if ((error = zfsvfs_teardown(zfsvfs, B_FALSE)) != 0)
                return (error);

        return (0);
}

/*
 * Rebuild SA and release VOPs.  Note that ownership of the underlying dataset
 * is an invariant across any of the operations that can be performed while the
 * filesystem was suspended.  Whether it succeeded or failed, the preconditions
 * are the same: the relevant objset and associated dataset are owned by
 * zfsvfs, held, and long held on entry.
 */
int
zfs_resume_fs(zfsvfs_t *zfsvfs, dsl_dataset_t *ds)
{
        int err;
        znode_t *zp;

        ASSERT(RRM_WRITE_HELD(&zfsvfs->z_teardown_lock));
        ASSERT(RW_WRITE_HELD(&zfsvfs->z_teardown_inactive_lock));

        /*
         * We already own this, so just update the objset_t, as the one we
         * had before may have been evicted.
         */
        objset_t *os;
        VERIFY3P(ds->ds_owner, ==, zfsvfs);
        VERIFY(dsl_dataset_long_held(ds));
        VERIFY0(dmu_objset_from_ds(ds, &os));

        err = zfsvfs_init(zfsvfs, os);
        if (err != 0)
                goto bail;

        VERIFY(zfsvfs_setup(zfsvfs, B_FALSE) == 0);

        zfs_set_fuid_feature(zfsvfs);

        /*
         * Attempt to re-establish all the active znodes with
         * their dbufs.  If a zfs_rezget() fails, then we'll let
         * any potential callers discover that via ZFS_ENTER_VERIFY_VP
         * when they try to use their znode.
         */
        mutex_enter(&zfsvfs->z_znodes_lock);
        for (zp = list_head(&zfsvfs->z_all_znodes); zp;
            zp = list_next(&zfsvfs->z_all_znodes, zp)) {
                (void) zfs_rezget(zp);
        }
        mutex_exit(&zfsvfs->z_znodes_lock);

bail:
        /* release the VOPs */
        rw_exit(&zfsvfs->z_teardown_inactive_lock);
        rrm_exit(&zfsvfs->z_teardown_lock, FTAG);

        if (err) {
                /*
                 * Since we couldn't setup the sa framework, try to force
                 * unmount this file system.
                 */
                if (vn_vfswlock(zfsvfs->z_vfs->vfs_vnodecovered) == 0) {
                        vfs_ref(zfsvfs->z_vfs);
                        (void) dounmount(zfsvfs->z_vfs, MS_FORCE, curthread);
                }
        }
        return (err);
}

static void
zfs_freevfs(vfs_t *vfsp)
{
        zfsvfs_t *zfsvfs = vfsp->vfs_data;

#ifdef illumos
        /*
         * If this is a snapshot, we have an extra VFS_HOLD on our parent
         * from zfs_mount().  Release it here.  If we came through
         * zfs_mountroot() instead, we didn't grab an extra hold, so
         * skip the VFS_RELE for rootvfs.
         */
        if (zfsvfs->z_issnap && (vfsp != rootvfs))
                VFS_RELE(zfsvfs->z_parent->z_vfs);
#endif

        zfsvfs_free(zfsvfs);

        atomic_dec_32(&zfs_active_fs_count);
}

#ifdef __i386__
static int desiredvnodes_backup;
#endif

static void
zfs_vnodes_adjust(void)
{
#ifdef __i386__
        int newdesiredvnodes;

        desiredvnodes_backup = desiredvnodes;

        /*
         * We calculate newdesiredvnodes the same way it is done in
         * vntblinit(). If it is equal to desiredvnodes, it means that
         * it wasn't tuned by the administrator and we can tune it down.
         */
        newdesiredvnodes = min(maxproc + vm_cnt.v_page_count / 4, 2 *
            vm_kmem_size / (5 * (sizeof(struct vm_object) +
            sizeof(struct vnode))));
        if (newdesiredvnodes == desiredvnodes)
                desiredvnodes = (3 * newdesiredvnodes) / 4;
#endif
}

static void
zfs_vnodes_adjust_back(void)
{

#ifdef __i386__
        desiredvnodes = desiredvnodes_backup;
#endif
}

void
zfs_init(void)
{

        printf("ZFS filesystem version: " ZPL_VERSION_STRING "\n");

        /*
         * Initialize .zfs directory structures
         */
        zfsctl_init();

        /*
         * Initialize znode cache, vnode ops, etc...
         */
        zfs_znode_init();

        /*
         * Reduce number of vnodes. Originally number of vnodes is calculated
         * with UFS inode in mind. We reduce it here, because it's too big for
         * ZFS/i386.
         */
        zfs_vnodes_adjust();

        dmu_objset_register_type(DMU_OST_ZFS, zfs_space_delta_cb);
}

void
zfs_fini(void)
{
        zfsctl_fini();
        zfs_znode_fini();
        zfs_vnodes_adjust_back();
}

int
zfs_busy(void)
{
        return (zfs_active_fs_count != 0);
}

int
zfs_set_version(zfsvfs_t *zfsvfs, uint64_t newvers)
{
        int error;
        objset_t *os = zfsvfs->z_os;
        dmu_tx_t *tx;

        if (newvers < ZPL_VERSION_INITIAL || newvers > ZPL_VERSION)
                return (SET_ERROR(EINVAL));

        if (newvers < zfsvfs->z_version)
                return (SET_ERROR(EINVAL));

        if (zfs_spa_version_map(newvers) >
            spa_version(dmu_objset_spa(zfsvfs->z_os)))
                return (SET_ERROR(ENOTSUP));

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_FALSE, ZPL_VERSION_STR);
        if (newvers >= ZPL_VERSION_SA && !zfsvfs->z_use_sa) {
                dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_TRUE,
                    ZFS_SA_ATTRS);
                dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
        }
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }

        error = zap_update(os, MASTER_NODE_OBJ, ZPL_VERSION_STR,
            8, 1, &newvers, tx);

        if (error) {
                dmu_tx_commit(tx);
                return (error);
        }

        if (newvers >= ZPL_VERSION_SA && !zfsvfs->z_use_sa) {
                uint64_t sa_obj;

                ASSERT3U(spa_version(dmu_objset_spa(zfsvfs->z_os)), >=,
                    SPA_VERSION_SA);
                sa_obj = zap_create(os, DMU_OT_SA_MASTER_NODE,
                    DMU_OT_NONE, 0, tx);

                error = zap_add(os, MASTER_NODE_OBJ,
                    ZFS_SA_ATTRS, 8, 1, &sa_obj, tx);
                ASSERT0(error);

                VERIFY(0 == sa_set_sa_object(os, sa_obj));
                sa_register_update_callback(os, zfs_sa_upgrade);
        }

        spa_history_log_internal_ds(dmu_objset_ds(os), "upgrade", tx,
            "from %llu to %llu", zfsvfs->z_version, newvers);

        dmu_tx_commit(tx);

        zfsvfs->z_version = newvers;

        zfs_set_fuid_feature(zfsvfs);

        return (0);
}

/*
 * Read a property stored within the master node.
 */
int
zfs_get_zplprop(objset_t *os, zfs_prop_t prop, uint64_t *value)
{
        const char *pname;
        int error = ENOENT;

        /*
         * Look up the file system's value for the property.  For the
         * version property, we look up a slightly different string.
         */
        if (prop == ZFS_PROP_VERSION)
                pname = ZPL_VERSION_STR;
        else
                pname = zfs_prop_to_name(prop);

        if (os != NULL) {
                ASSERT3U(os->os_phys->os_type, ==, DMU_OST_ZFS);
                error = zap_lookup(os, MASTER_NODE_OBJ, pname, 8, 1, value);
        }

        if (error == ENOENT) {
                /* No value set, use the default value */
                switch (prop) {
                case ZFS_PROP_VERSION:
                        *value = ZPL_VERSION;
                        break;
                case ZFS_PROP_NORMALIZE:
                case ZFS_PROP_UTF8ONLY:
                        *value = 0;
                        break;
                case ZFS_PROP_CASE:
                        *value = ZFS_CASE_SENSITIVE;
                        break;
                default:
                        return (error);
                }
                error = 0;
        }
        return (error);
}

/*
 * Return true if the coresponding vfs's unmounted flag is set.
 * Otherwise return false.
 * If this function returns true we know VFS unmount has been initiated.
 */
boolean_t
zfs_get_vfs_flag_unmounted(objset_t *os)
{
        zfsvfs_t *zfvp;
        boolean_t unmounted = B_FALSE;

        ASSERT(dmu_objset_type(os) == DMU_OST_ZFS);

        mutex_enter(&os->os_user_ptr_lock);
        zfvp = dmu_objset_get_user(os);
        if (zfvp != NULL && zfvp->z_vfs != NULL &&
            (zfvp->z_vfs->mnt_kern_flag & MNTK_UNMOUNT))
                unmounted = B_TRUE;
        mutex_exit(&os->os_user_ptr_lock);

        return (unmounted);
}

#ifdef _KERNEL
void
zfsvfs_update_fromname(const char *oldname, const char *newname)
{
        char tmpbuf[MAXPATHLEN];
        struct mount *mp;
        char *fromname;
        size_t oldlen;

        oldlen = strlen(oldname);

        mtx_lock(&mountlist_mtx);
        TAILQ_FOREACH(mp, &mountlist, mnt_list) {
                fromname = mp->mnt_stat.f_mntfromname;
                if (strcmp(fromname, oldname) == 0) {
                        (void)strlcpy(fromname, newname,
                            sizeof(mp->mnt_stat.f_mntfromname));
                        continue;
                }
                if (strncmp(fromname, oldname, oldlen) == 0 &&
                    (fromname[oldlen] == '/' || fromname[oldlen] == '@')) {
                        (void)snprintf(tmpbuf, sizeof(tmpbuf), "%s%s",
                            newname, fromname + oldlen);
                        (void)strlcpy(fromname, tmpbuf,
                            sizeof(mp->mnt_stat.f_mntfromname));
                        continue;
                }
        }
        mtx_unlock(&mountlist_mtx);
}
#endif