freebsd/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_vnops.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/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/dmu_objset.h>
#include <sys/dsl_dir.h>
#include <sys/spa_boot.h>
#include <sys/jail.h>
#include <ufs/ufs/quota.h>
#include <sys/zfs_quota.h>

#include "zfs_comutil.h"

#ifndef	MNTK_VMSETSIZE_BUG
#define	MNTK_VMSETSIZE_BUG	0
#endif
#ifndef	MNTK_NOMSYNC
#define	MNTK_NOMSYNC	8
#endif

/* BEGIN CSTYLED */
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");
/* END CSTYLED */

#if __FreeBSD_version >= 1400018
static int zfs_quotactl(vfs_t *vfsp, int cmds, uid_t id, void *arg,
    bool *mp_busy);
#else
static int zfs_quotactl(vfs_t *vfsp, int cmds, uid_t id, void *arg);
#endif
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);
#if __FreeBSD_version >= 1300098
static int zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, uint64_t *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int *secflavors);
#else
static int zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, int *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int **secflavors);
#endif
static int zfs_fhtovp(vfs_t *vfsp, fid_t *fidp, int flags, vnode_t **vpp);
static void zfs_freevfs(vfs_t *vfsp);

struct vfsops zfs_vfsops = {
	.vfs_mount =		zfs_mount,
	.vfs_unmount =		zfs_umount,
#if __FreeBSD_version >= 1300049
	.vfs_root =		vfs_cache_root,
	.vfs_cachedroot = zfs_root,
#else
	.vfs_root =		zfs_root,
#endif
	.vfs_statfs =		zfs_statfs,
	.vfs_vget =		zfs_vget,
	.vfs_sync =		zfs_sync,
	.vfs_checkexp =		zfs_checkexp,
	.vfs_fhtovp =		zfs_fhtovp,
	.vfs_quotactl =		zfs_quotactl,
};

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;

int
zfs_get_temporary_prop(dsl_dataset_t *ds, zfs_prop_t zfs_prop, uint64_t *val,
    char *setpoint)
{
	int error;
	zfsvfs_t *zfvp;
	vfs_t *vfsp;
	objset_t *os;
	uint64_t tmp = *val;

	error = dmu_objset_from_ds(ds, &os);
	if (error != 0)
		return (error);

	error = getzfsvfs_impl(os, &zfvp);
	if (error != 0)
		return (error);
	if (zfvp == NULL)
		return (ENOENT);
	vfsp = zfvp->z_vfs;
	switch (zfs_prop) {
	case ZFS_PROP_ATIME:
		if (vfs_optionisset(vfsp, MNTOPT_NOATIME, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_ATIME, NULL))
			tmp = 1;
		break;
	case ZFS_PROP_DEVICES:
		if (vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_DEVICES, NULL))
			tmp = 1;
		break;
	case ZFS_PROP_EXEC:
		if (vfs_optionisset(vfsp, MNTOPT_NOEXEC, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_EXEC, NULL))
			tmp = 1;
		break;
	case ZFS_PROP_SETUID:
		if (vfs_optionisset(vfsp, MNTOPT_NOSETUID, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_SETUID, NULL))
			tmp = 1;
		break;
	case ZFS_PROP_READONLY:
		if (vfs_optionisset(vfsp, MNTOPT_RW, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_RO, NULL))
			tmp = 1;
		break;
	case ZFS_PROP_XATTR:
		if (zfvp->z_flags & ZSB_XATTR)
			tmp = zfvp->z_xattr;
		break;
	case ZFS_PROP_NBMAND:
		if (vfs_optionisset(vfsp, MNTOPT_NONBMAND, NULL))
			tmp = 0;
		if (vfs_optionisset(vfsp, MNTOPT_NBMAND, NULL))
			tmp = 1;
		break;
	default:
		vfs_unbusy(vfsp);
		return (ENOENT);
	}

	vfs_unbusy(vfsp);
	if (tmp != *val) {
		(void) strcpy(setpoint, "temporary");
		*val = tmp;
	}
	return (0);
}

static int
zfs_getquota(zfsvfs_t *zfsvfs, uid_t id, int isgroup, struct dqblk64 *dqp)
{
	int error = 0;
	char buf[32];
	uint64_t usedobj, quotaobj;
	uint64_t quota, used = 0;
	timespec_t now;

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

	if (quotaobj == 0 || zfsvfs->z_replay) {
		error = ENOENT;
		goto done;
	}
	(void) sprintf(buf, "%llx", (longlong_t)id);
	if ((error = zap_lookup(zfsvfs->z_os, quotaobj,
	    buf, sizeof (quota), 1, &quota)) != 0) {
		dprintf("%s(%d): quotaobj lookup failed\n",
		    __FUNCTION__, __LINE__);
		goto done;
	}
	/*
	 * quota(8) uses bsoftlimit as "quoota", and hardlimit as "limit".
	 * So we set them to be the same.
	 */
	dqp->dqb_bsoftlimit = dqp->dqb_bhardlimit = btodb(quota);
	error = zap_lookup(zfsvfs->z_os, usedobj, buf, sizeof (used), 1, &used);
	if (error && error != ENOENT) {
		dprintf("%s(%d):  usedobj failed; %d\n",
		    __FUNCTION__, __LINE__, error);
		goto done;
	}
	dqp->dqb_curblocks = btodb(used);
	dqp->dqb_ihardlimit = dqp->dqb_isoftlimit = 0;
	vfs_timestamp(&now);
	/*
	 * Setting this to 0 causes FreeBSD quota(8) to print
	 * the number of days since the epoch, which isn't
	 * particularly useful.
	 */
	dqp->dqb_btime = dqp->dqb_itime = now.tv_sec;
done:
	return (error);
}

static int
#if __FreeBSD_version >= 1400018
zfs_quotactl(vfs_t *vfsp, int cmds, uid_t id, void *arg, bool *mp_busy)
#else
zfs_quotactl(vfs_t *vfsp, int cmds, uid_t id, void *arg)
#endif
{
	zfsvfs_t *zfsvfs = vfsp->vfs_data;
	struct thread *td;
	int cmd, type, error = 0;
	int bitsize;
	zfs_userquota_prop_t quota_type;
	struct dqblk64 dqblk = { 0 };

	td = curthread;
	cmd = cmds >> SUBCMDSHIFT;
	type = cmds & SUBCMDMASK;

	ZFS_ENTER(zfsvfs);
	if (id == -1) {
		switch (type) {
		case USRQUOTA:
			id = td->td_ucred->cr_ruid;
			break;
		case GRPQUOTA:
			id = td->td_ucred->cr_rgid;
			break;
		default:
			error = EINVAL;
#if __FreeBSD_version < 1400018
			if (cmd == Q_QUOTAON || cmd == Q_QUOTAOFF)
				vfs_unbusy(vfsp);
#endif
			goto done;
		}
	}
	/*
	 * Map BSD type to:
	 * ZFS_PROP_USERUSED,
	 * ZFS_PROP_USERQUOTA,
	 * ZFS_PROP_GROUPUSED,
	 * ZFS_PROP_GROUPQUOTA
	 */
	switch (cmd) {
	case Q_SETQUOTA:
	case Q_SETQUOTA32:
		if (type == USRQUOTA)
			quota_type = ZFS_PROP_USERQUOTA;
		else if (type == GRPQUOTA)
			quota_type = ZFS_PROP_GROUPQUOTA;
		else
			error = EINVAL;
		break;
	case Q_GETQUOTA:
	case Q_GETQUOTA32:
		if (type == USRQUOTA)
			quota_type = ZFS_PROP_USERUSED;
		else if (type == GRPQUOTA)
			quota_type = ZFS_PROP_GROUPUSED;
		else
			error = EINVAL;
		break;
	}

	/*
	 * Depending on the cmd, we may need to get
	 * the ruid and domain (see fuidstr_to_sid?),
	 * the fuid (how?), or other information.
	 * Create fuid using zfs_fuid_create(zfsvfs, id,
	 * ZFS_OWNER or ZFS_GROUP, cr, &fuidp)?
	 * I think I can use just the id?
	 *
	 * Look at zfs_id_overquota() to look up a quota.
	 * zap_lookup(something, quotaobj, fuidstring,
	 *     sizeof (long long), 1, &quota)
	 *
	 * See zfs_set_userquota() to set a quota.
	 */
	if ((uint32_t)type >= MAXQUOTAS) {
		error = EINVAL;
		goto done;
	}

	switch (cmd) {
	case Q_GETQUOTASIZE:
		bitsize = 64;
		error = copyout(&bitsize, arg, sizeof (int));
		break;
	case Q_QUOTAON:
		// As far as I can tell, you can't turn quotas on or off on zfs
		error = 0;
#if __FreeBSD_version < 1400018
		vfs_unbusy(vfsp);
#endif
		break;
	case Q_QUOTAOFF:
		error = ENOTSUP;
#if __FreeBSD_version < 1400018
		vfs_unbusy(vfsp);
#endif
		break;
	case Q_SETQUOTA:
		error = copyin(arg, &dqblk, sizeof (dqblk));
		if (error == 0)
			error = zfs_set_userquota(zfsvfs, quota_type,
			    "", id, dbtob(dqblk.dqb_bhardlimit));
		break;
	case Q_GETQUOTA:
		error = zfs_getquota(zfsvfs, id, type == GRPQUOTA, &dqblk);
		if (error == 0)
			error = copyout(&dqblk, arg, sizeof (dqblk));
		break;
	default:
		error = EINVAL;
		break;
	}
done:
	ZFS_EXIT(zfsvfs);
	return (error);
}


boolean_t
zfs_is_readonly(zfsvfs_t *zfsvfs)
{
	return (!!(zfsvfs->z_vfs->vfs_flag & VFS_RDONLY));
}

/*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 (rebooting && 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(8).  Unlike other filesystems, ZFS honors the
		 * request by waiting for all pools to commit all dirty data.
		 */
		spa_sync_allpools();
	}

	return (0);
}

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 == ZFS_XATTR_OFF) {
		zfsvfs->z_flags &= ~ZSB_XATTR;
	} else {
		zfsvfs->z_flags |= ZSB_XATTR;

		if (newval == ZFS_XATTR_SA)
			zfsvfs->z_xattr_sa = B_TRUE;
		else
			zfsvfs->z_xattr_sa = B_FALSE;
	}
}

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

	zfsvfs->z_acl_type = 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;
	boolean_t xattr = B_FALSE;
	boolean_t atime = B_FALSE;
	boolean_t do_atime = B_FALSE;
	boolean_t do_xattr = B_FALSE;
	int error = 0;

	ASSERT3P(vfsp, !=, NULL);
	zfsvfs = vfsp->vfs_data;
	ASSERT3P(zfsvfs, !=, NULL);
	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_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)) {
		zfsvfs->z_xattr = xattr = ZFS_XATTR_OFF;
		do_xattr = B_TRUE;
	} else if (vfs_optionisset(vfsp, MNTOPT_XATTR, NULL)) {
		zfsvfs->z_xattr = xattr = ZFS_XATTR_DIR;
		do_xattr = B_TRUE;
	} else if (vfs_optionisset(vfsp, MNTOPT_DIRXATTR, NULL)) {
		zfsvfs->z_xattr = xattr = ZFS_XATTR_DIR;
		do_xattr = B_TRUE;
	} else if (vfs_optionisset(vfsp, MNTOPT_SAXATTR, NULL)) {
		zfsvfs->z_xattr = xattr = ZFS_XATTR_SA;
		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);
	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_ACLTYPE), acl_type_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);
	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);
}

/*
 * 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;

	error = zfs_get_zplprop(os, ZFS_PROP_ACLTYPE, &val);
	if (error != 0)
		return (error);
	zfsvfs->z_acl_type = (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 = zfs_get_zplprop(os, ZFS_PROP_XATTR, &val);
		if (error == 0 && val == ZFS_XATTR_SA)
			zfsvfs->z_xattr_sa = B_TRUE;
	}

	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);
	ASSERT3U(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_userquota_prop_prefixes[ZFS_PROP_PROJECTQUOTA],
	    8, 1, &zfsvfs->z_projectquota_obj);
	if (error == ENOENT)
		zfsvfs->z_projectquota_obj = 0;
	else if (error != 0)
		return (error);

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

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

	error = zap_lookup(os, MASTER_NODE_OBJ,
	    zfs_userquota_prop_prefixes[ZFS_PROP_PROJECTOBJQUOTA],
	    8, 1, &zfsvfs->z_projectobjquota_obj);
	if (error == ENOENT)
		zfsvfs->z_projectobjquota_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);
}

taskq_t *zfsvfs_taskq;

static void
zfsvfs_task_unlinked_drain(void *context, int pending __unused)
{

	zfs_unlinked_drain((zfsvfs_t *)context);
}

int
zfsvfs_create(const char *osname, boolean_t readonly, zfsvfs_t **zfvp)
{
	objset_t *os;
	zfsvfs_t *zfsvfs;
	int error;
	boolean_t ro = (readonly || (strchr(osname, '@') != NULL));

	/*
	 * 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);

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

	error = zfsvfs_create_impl(zfvp, zfsvfs, os);

	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));
	TASK_INIT(&zfsvfs->z_unlinked_drain_task, 0,
	    zfsvfs_task_unlinked_drain, zfsvfs);
	ZFS_TEARDOWN_INIT(zfsvfs);
	ZFS_TEARDOWN_INACTIVE_INIT(zfsvfs);
	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) {
		dmu_objset_disown(os, B_TRUE, zfsvfs);
		*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;

	/*
	 * Check for a bad on-disk format version now since we
	 * lied about owning the dataset readonly before.
	 */
	if (!(zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) &&
	    dmu_objset_incompatible_encryption_version(zfsvfs->z_os))
		return (SET_ERROR(EROFS));

	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;

		ASSERT3P(zfsvfs->z_kstat.dk_kstats, ==, NULL);
		dataset_kstats_create(&zfsvfs->z_kstat, zfsvfs->z_os);

		/*
		 * 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 {
			dsl_dir_t *dd;
			zap_stats_t zs;

			if (zap_get_stats(zfsvfs->z_os, zfsvfs->z_unlinkedobj,
			    &zs) == 0) {
				dataset_kstats_update_nunlinks_kstat(
				    &zfsvfs->z_kstat, zs.zs_num_entries);
				dprintf_ds(zfsvfs->z_os->os_dsl_dataset,
				    "num_entries in unlinked set: %llu",
				    (u_longlong_t)zs.zs_num_entries);
			}

			zfs_unlinked_drain(zfsvfs);
			dd = zfsvfs->z_os->os_dsl_dataset->ds_dir;
			dd->dd_activity_cancelled = B_FALSE;
		}

		/*
		 * 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 {
				boolean_t use_nc = zfsvfs->z_use_namecache;
				zfsvfs->z_use_namecache = B_FALSE;
				zfsvfs->z_replay = B_TRUE;
				zil_replay(zfsvfs->z_os, zfsvfs,
				    zfs_replay_vector);
				zfsvfs->z_replay = B_FALSE;
				zfsvfs->z_use_namecache = use_nc;
			}
		}

		/* restore readonly bit */
		if (readonly != 0)
			zfsvfs->z_vfs->vfs_flag |= VFS_RDONLY;
	}

	/*
	 * 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);
}

void
zfsvfs_free(zfsvfs_t *zfsvfs)
{
	int i;

	zfs_fuid_destroy(zfsvfs);

	mutex_destroy(&zfsvfs->z_znodes_lock);
	mutex_destroy(&zfsvfs->z_lock);
	ASSERT3U(zfsvfs->z_nr_znodes, ==, 0);
	list_destroy(&zfsvfs->z_all_znodes);
	ZFS_TEARDOWN_DESTROY(zfsvfs);
	ZFS_TEARDOWN_INACTIVE_DESTROY(zfsvfs);
	rw_destroy(&zfsvfs->z_fuid_lock);
	for (i = 0; i != ZFS_OBJ_MTX_SZ; i++)
		mutex_destroy(&zfsvfs->z_hold_mtx[i]);
	dataset_kstats_destroy(&zfsvfs->z_kstat);
	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;

	ASSERT3P(vfsp, !=, NULL);
	ASSERT3P(osname, !=, NULL);

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

	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;
	/*
	 * This can cause a loss of coherence between ARC and page cache
	 * on ZoF - unclear if the problem is in FreeBSD or ZoF
	 */
	vfsp->mnt_kern_flag |= MNTK_NO_IOPF;	/* vn_io_fault can be used */
	vfsp->mnt_kern_flag |= MNTK_NOMSYNC;
	vfsp->mnt_kern_flag |= MNTK_VMSETSIZE_BUG;

#if defined(_KERNEL) && !defined(KMEM_DEBUG)
	vfsp->mnt_kern_flag |= MNTK_FPLOOKUP;
#endif
	/*
	 * 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);
	ASSERT3U((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);
		if ((error = dsl_prop_get_integer(osname,
		    "acltype", &pval, NULL)))
			goto out;
		acl_type_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 {
		if ((error = zfsvfs_setup(zfsvfs, B_TRUE)))
			goto out;
	}

	vfs_mountedfrom(vfsp, osname);

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

	return (error);
}

static 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);
}

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);
}

static void
fetch_osname_options(char *name, bool *checkpointrewind)
{

	if (name[0] == '!') {
		*checkpointrewind = true;
		memmove(name, name + 1, strlen(name));
	} else {
		*checkpointrewind = false;
	}
}

/*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;
	bool		checkpointrewind;

	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);
	}

	fetch_osname_options(osname, &checkpointrewind);

	/*
	 * 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_UNLOCK1(mvp);
				goto out;
			}

			if (secpolicy_vnode_owner(mvp, cr, vattr.va_uid) != 0 &&
			    VOP_ACCESS(mvp, VWRITE, cr, td) != 0) {
				VOP_UNLOCK1(mvp);
				goto out;
			}
			VOP_UNLOCK1(mvp);
		}

		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(curproc) &&
	    (!zone_dataset_visible(osname, &canwrite) || !canwrite)) {
		error = SET_ERROR(EPERM);
		goto out;
	}

	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().
		 */
		ZFS_TEARDOWN_ENTER_WRITE(zfsvfs, FTAG);
		zfs_unregister_callbacks(zfsvfs);
		error = zfs_register_callbacks(vfsp);
		ZFS_TEARDOWN_EXIT(zfsvfs, 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, checkpointrewind);
		if (error)
			goto out;
	}
	DROP_GIANT();
	error = zfs_domount(vfsp, osname);
	PICKUP_GIANT();

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.
	 */
	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;
	dsl_dir_t *dd;

	/*
	 * If someone has not already unmounted this file system,
	 * drain the zrele_taskq to ensure all active references to the
	 * zfsvfs_t have been handled only then can it be safely destroyed.
	 */
	if (zfsvfs->z_os) {
		/*
		 * If we're unmounting we have to wait for the list to
		 * drain completely.
		 *
		 * If we're not unmounting there's no guarantee the list
		 * will drain completely, but zreles run from the taskq
		 * may add the parents of dir-based xattrs to the taskq
		 * so we want to wait for these.
		 *
		 * We can safely read z_nr_znodes without locking because the
		 * VFS has already blocked operations which add to the
		 * z_all_znodes list and thus increment z_nr_znodes.
		 */
		int round = 0;
		while (zfsvfs->z_nr_znodes > 0) {
			taskq_wait_outstanding(dsl_pool_zrele_taskq(
			    dmu_objset_pool(zfsvfs->z_os)), 0);
			if (++round > 1 && !unmounting)
				break;
		}
	}
	ZFS_TEARDOWN_ENTER_WRITE(zfsvfs, 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.
		 */
#ifdef FREEBSD_NAMECACHE
#if __FreeBSD_version >= 1300117
		cache_purgevfs(zfsvfs->z_parent->z_vfs);
#else
		cache_purgevfs(zfsvfs->z_parent->z_vfs, true);
#endif
#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;
	}

	ZFS_TEARDOWN_INACTIVE_ENTER_WRITE(zfsvfs);

	/*
	 * 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)) {
		ZFS_TEARDOWN_INACTIVE_EXIT_WRITE(zfsvfs);
		ZFS_TEARDOWN_EXIT(zfsvfs, 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
	 * relevant 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 != NULL) {
			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;
		ZFS_TEARDOWN_INACTIVE_EXIT_WRITE(zfsvfs);
		ZFS_TEARDOWN_EXIT(zfsvfs, 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 (!zfs_is_readonly(zfsvfs))
		txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), 0);
	dmu_objset_evict_dbufs(zfsvfs->z_os);
	dd = zfsvfs->z_os->os_dsl_dataset->ds_dir;
	dsl_dir_cancel_waiters(dd);

	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 *)vfsp->vfs_resource,
		    ZFS_DELEG_PERM_MOUNT, cr))
			return (ret);
	}

	/*
	 * 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.
		 */
		ZFS_TEARDOWN_ENTER_WRITE(zfsvfs, FTAG);
		zfsvfs->z_unmounted = B_TRUE;
		ZFS_TEARDOWN_EXIT(zfsvfs, FTAG);
	}

	/*
	 * Flush all the files.
	 */
	ret = vflush(vfsp, 0, (fflag & MS_FORCE) ? FORCECLOSE : 0, td);
	if (ret != 0)
		return (ret);
	while (taskqueue_cancel(zfsvfs_taskq->tq_queue,
	    &zfsvfs->z_unlinked_drain_task, NULL) != 0)
		taskqueue_drain(zfsvfs_taskq->tq_queue,
		    &zfsvfs->z_unlinked_drain_task);

	VERIFY0(zfsvfs_teardown(zfsvfs, B_TRUE));
	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, B_TRUE, 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)
			vrele(*vpp);
	}
	if (err != 0)
		*vpp = NULL;
	return (err);
}

static int
#if __FreeBSD_version >= 1300098
zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, uint64_t *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int *secflavors)
#else
zfs_checkexp(vfs_t *vfsp, struct sockaddr *nam, int *extflagsp,
    struct ucred **credanonp, int *numsecflavors, int **secflavors)
#endif
{
	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 [%llu mask %llx]\n", (u_longlong_t)object,
	    (u_longlong_t)fid_gen,
	    (u_longlong_t)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 (%llu) != fid gen (%llu)\n",
		    (u_longlong_t)zp_gen, (u_longlong_t)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(ZFS_TEARDOWN_WRITE_HELD(zfsvfs));
	ASSERT(ZFS_TEARDOWN_INACTIVE_WRITE_HELD(zfsvfs));

	/*
	 * 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));
	dsl_pool_t *dp = spa_get_dsl(dsl_dataset_get_spa(ds));
	dsl_pool_config_enter(dp, FTAG);
	VERIFY0(dmu_objset_from_ds(ds, &os));
	dsl_pool_config_exit(dp, FTAG);

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

	ds->ds_dir->dd_activity_cancelled = B_FALSE;
	VERIFY0(zfsvfs_setup(zfsvfs, B_FALSE));

	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 */
	ZFS_TEARDOWN_INACTIVE_EXIT_WRITE(zfsvfs);
	ZFS_TEARDOWN_EXIT(zfsvfs, 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;

	zfsvfs_free(zfsvfs);

	atomic_dec_32(&zfs_active_fs_count);
}

#ifdef __i386__
static int desiredvnodes_backup;
#include <sys/vmmeter.h>


#include <vm/vm_page.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#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, zpl_get_file_info);

	zfsvfs_taskq = taskq_create("zfsvfs", 1, minclsyspri, 0, 0, 0);
}

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

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

/*
 * Release VOPs and unmount a suspended filesystem.
 */
int
zfs_end_fs(zfsvfs_t *zfsvfs, dsl_dataset_t *ds)
{
	ASSERT(ZFS_TEARDOWN_WRITE_HELD(zfsvfs));
	ASSERT(ZFS_TEARDOWN_INACTIVE_WRITE_HELD(zfsvfs));

	/*
	 * We already own this, so just hold and rele it to 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));
	dsl_pool_t *dp = spa_get_dsl(dsl_dataset_get_spa(ds));
	dsl_pool_config_enter(dp, FTAG);
	VERIFY0(dmu_objset_from_ds(ds, &os));
	dsl_pool_config_exit(dp, FTAG);
	zfsvfs->z_os = os;

	/* release the VOPs */
	ZFS_TEARDOWN_INACTIVE_EXIT_WRITE(zfsvfs);
	ZFS_TEARDOWN_EXIT(zfsvfs, FTAG);

	/*
	 * Try to force unmount this file system.
	 */
	(void) zfs_umount(zfsvfs->z_vfs, 0);
	zfsvfs->z_unmounted = B_TRUE;
	return (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);

		VERIFY0(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 %ju to %ju", (uintmax_t)zfsvfs->z_version,
	    (uintmax_t)newvers);
	dmu_tx_commit(tx);

	zfsvfs->z_version = newvers;
	os->os_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)
{
	uint64_t *cached_copy = NULL;

	/*
	 * Figure out where in the objset_t the cached copy would live, if it
	 * is available for the requested property.
	 */
	if (os != NULL) {
		switch (prop) {
		case ZFS_PROP_VERSION:
			cached_copy = &os->os_version;
			break;
		case ZFS_PROP_NORMALIZE:
			cached_copy = &os->os_normalization;
			break;
		case ZFS_PROP_UTF8ONLY:
			cached_copy = &os->os_utf8only;
			break;
		case ZFS_PROP_CASE:
			cached_copy = &os->os_casesensitivity;
			break;
		default:
			break;
		}
	}
	if (cached_copy != NULL && *cached_copy != OBJSET_PROP_UNINITIALIZED) {
		*value = *cached_copy;
		return (0);
	}

	/*
	 * If the property wasn't cached, look up the file system's value for
	 * the property. For the version property, we look up a slightly
	 * different string.
	 */
	const char *pname;
	int error = ENOENT;
	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;
		case ZFS_PROP_ACLTYPE:
			*value = ZFS_ACLTYPE_NFSV4;
			break;
		default:
			return (error);
		}
		error = 0;
	}

	/*
	 * If one of the methods for getting the property value above worked,
	 * copy it into the objset_t's cache.
	 */
	if (error == 0 && cached_copy != NULL) {
		*cached_copy = *value;
	}

	return (error);
}

/*
 * Return true if the corresponding 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;

	ASSERT3U(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