xref: /titanic_54/usr/src/uts/common/fs/vfs.c (revision e373b6e444a487df89a5dc6a4a4030b5b2aa87f9)

/*
 * 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) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2014, Joyent, Inc. All rights reserved.
 * Copyright 2017 RackTop Systems.
 * Copyright 2016 Nexenta Systems, Inc.
 */

/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#include <sys/types.h>
#include <sys/t_lock.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/user.h>
#include <sys/fstyp.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/fem.h>
#include <sys/mntent.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/statfs.h>
#include <sys/cred.h>
#include <sys/vnode.h>
#include <sys/rwstlock.h>
#include <sys/dnlc.h>
#include <sys/file.h>
#include <sys/time.h>
#include <sys/atomic.h>
#include <sys/cmn_err.h>
#include <sys/buf.h>
#include <sys/swap.h>
#include <sys/debug.h>
#include <sys/vnode.h>
#include <sys/modctl.h>
#include <sys/ddi.h>
#include <sys/pathname.h>
#include <sys/bootconf.h>
#include <sys/dumphdr.h>
#include <sys/dc_ki.h>
#include <sys/poll.h>
#include <sys/sunddi.h>
#include <sys/sysmacros.h>
#include <sys/zone.h>
#include <sys/policy.h>
#include <sys/ctfs.h>
#include <sys/objfs.h>
#include <sys/console.h>
#include <sys/reboot.h>
#include <sys/attr.h>
#include <sys/zio.h>
#include <sys/spa.h>
#include <sys/lofi.h>
#include <sys/bootprops.h>
#include <sys/avl.h>

#include <vm/page.h>

#include <fs/fs_subr.h>
/* Private interfaces to create vopstats-related data structures */
extern void		initialize_vopstats(vopstats_t *);
extern vopstats_t	*get_fstype_vopstats(struct vfs *, struct vfssw *);
extern vsk_anchor_t	*get_vskstat_anchor(struct vfs *);

static void vfs_clearmntopt_nolock(mntopts_t *, const char *, int);
static void vfs_setmntopt_nolock(mntopts_t *, const char *,
    const char *, int, int);
static int  vfs_optionisset_nolock(const mntopts_t *, const char *, char **);
static void vfs_freemnttab(struct vfs *);
static void vfs_freeopt(mntopt_t *);
static void vfs_swapopttbl_nolock(mntopts_t *, mntopts_t *);
static void vfs_swapopttbl(mntopts_t *, mntopts_t *);
static void vfs_copyopttbl_extend(const mntopts_t *, mntopts_t *, int);
static void vfs_createopttbl_extend(mntopts_t *, const char *,
    const mntopts_t *);
static char **vfs_copycancelopt_extend(char **const, int);
static void vfs_freecancelopt(char **);
static void getrootfs(char **, char **);
static int getmacpath(dev_info_t *, void *);
static void vfs_mnttabvp_setup(void);

struct ipmnt {
	struct ipmnt	*mip_next;
	dev_t		mip_dev;
	struct vfs	*mip_vfsp;
};

static kmutex_t		vfs_miplist_mutex;
static struct ipmnt	*vfs_miplist = NULL;
static struct ipmnt	*vfs_miplist_end = NULL;

static kmem_cache_t *vfs_cache;	/* Pointer to VFS kmem cache */

/*
 * VFS global data.
 */
vnode_t *rootdir;		/* pointer to root inode vnode. */
vnode_t *devicesdir;		/* pointer to inode of devices root */
vnode_t	*devdir;		/* pointer to inode of dev root */

char *server_rootpath;		/* root path for diskless clients */
char *server_hostname;		/* hostname of diskless server */

static struct vfs root;
static struct vfs devices;
static struct vfs dev;
struct vfs *rootvfs = &root;	/* pointer to root vfs; head of VFS list. */
avl_tree_t vfs_by_dev;		/* avl tree to index mounted VFSs by dev */
avl_tree_t vfs_by_mntpnt;	/* avl tree to index mounted VFSs by mntpnt */
uint64_t vfs_curr_mntix;	/* counter to provide a unique mntix for
				 * entries in the above avl trees.
				 * protected by vfslist lock */
rvfs_t *rvfs_list;		/* array of vfs ptrs for vfs hash list */
int vfshsz = 512;		/* # of heads/locks in vfs hash arrays */
				/* must be power of 2!	*/
timespec_t vfs_mnttab_ctime;	/* mnttab created time */
timespec_t vfs_mnttab_mtime;	/* mnttab last modified time */
char *vfs_dummyfstype = "\0";
struct pollhead vfs_pollhd;	/* for mnttab pollers */
struct vnode *vfs_mntdummyvp;	/* to fake mnttab read/write for file events */
int	mntfstype;		/* will be set once mnt fs is mounted */

/*
 * Table for generic options recognized in the VFS layer and acted
 * on at this level before parsing file system specific options.
 * The nosuid option is stronger than any of the devices and setuid
 * options, so those are canceled when nosuid is seen.
 *
 * All options which are added here need to be added to the
 * list of standard options in usr/src/cmd/fs.d/fslib.c as well.
 */
/*
 * VFS Mount options table
 */
static char *ro_cancel[] = { MNTOPT_RW, NULL };
static char *rw_cancel[] = { MNTOPT_RO, NULL };
static char *suid_cancel[] = { MNTOPT_NOSUID, NULL };
static char *nosuid_cancel[] = { MNTOPT_SUID, MNTOPT_DEVICES, MNTOPT_NODEVICES,
    MNTOPT_NOSETUID, MNTOPT_SETUID, NULL };
static char *devices_cancel[] = { MNTOPT_NODEVICES, NULL };
static char *nodevices_cancel[] = { MNTOPT_DEVICES, NULL };
static char *setuid_cancel[] = { MNTOPT_NOSETUID, NULL };
static char *nosetuid_cancel[] = { MNTOPT_SETUID, NULL };
static char *nbmand_cancel[] = { MNTOPT_NONBMAND, NULL };
static char *nonbmand_cancel[] = { MNTOPT_NBMAND, NULL };
static char *exec_cancel[] = { MNTOPT_NOEXEC, NULL };
static char *noexec_cancel[] = { MNTOPT_EXEC, NULL };

static const mntopt_t mntopts[] = {
/*
 *	option name		cancel options		default arg	flags
 */
	{ MNTOPT_REMOUNT,	NULL,			NULL,
		MO_NODISPLAY, (void *)0 },
	{ MNTOPT_RO,		ro_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_RW,		rw_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_SUID,		suid_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_NOSUID,	nosuid_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_DEVICES,	devices_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_NODEVICES,	nodevices_cancel,	NULL,		0,
		(void *)0 },
	{ MNTOPT_SETUID,	setuid_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_NOSETUID,	nosetuid_cancel,	NULL,		0,
		(void *)0 },
	{ MNTOPT_NBMAND,	nbmand_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_NONBMAND,	nonbmand_cancel,	NULL,		0,
		(void *)0 },
	{ MNTOPT_EXEC,		exec_cancel,		NULL,		0,
		(void *)0 },
	{ MNTOPT_NOEXEC,	noexec_cancel,		NULL,		0,
		(void *)0 },
};

const mntopts_t vfs_mntopts = {
	sizeof (mntopts) / sizeof (mntopt_t),
	(mntopt_t *)&mntopts[0]
};

/*
 * File system operation dispatch functions.
 */

int
fsop_mount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *cr)
{
	return (*(vfsp)->vfs_op->vfs_mount)(vfsp, mvp, uap, cr);
}

int
fsop_unmount(vfs_t *vfsp, int flag, cred_t *cr)
{
	return (*(vfsp)->vfs_op->vfs_unmount)(vfsp, flag, cr);
}

int
fsop_root(vfs_t *vfsp, vnode_t **vpp)
{
	refstr_t *mntpt;
	int ret = (*(vfsp)->vfs_op->vfs_root)(vfsp, vpp);
	/*
	 * Make sure this root has a path.  With lofs, it is possible to have
	 * a NULL mountpoint.
	 */
	if (ret == 0 && vfsp->vfs_mntpt != NULL && (*vpp)->v_path == NULL) {
		mntpt = vfs_getmntpoint(vfsp);
		vn_setpath_str(*vpp, refstr_value(mntpt),
		    strlen(refstr_value(mntpt)));
		refstr_rele(mntpt);
	}

	return (ret);
}

int
fsop_statfs(vfs_t *vfsp, statvfs64_t *sp)
{
	return (*(vfsp)->vfs_op->vfs_statvfs)(vfsp, sp);
}

int
fsop_sync(vfs_t *vfsp, short flag, cred_t *cr)
{
	return (*(vfsp)->vfs_op->vfs_sync)(vfsp, flag, cr);
}

int
fsop_vget(vfs_t *vfsp, vnode_t **vpp, fid_t *fidp)
{
	/*
	 * In order to handle system attribute fids in a manner
	 * transparent to the underlying fs, we embed the fid for
	 * the sysattr parent object in the sysattr fid and tack on
	 * some extra bytes that only the sysattr layer knows about.
	 *
	 * This guarantees that sysattr fids are larger than other fids
	 * for this vfs. If the vfs supports the sysattr view interface
	 * (as indicated by VFSFT_SYSATTR_VIEWS), we cannot have a size
	 * collision with XATTR_FIDSZ.
	 */
	if (vfs_has_feature(vfsp, VFSFT_SYSATTR_VIEWS) &&
	    fidp->fid_len == XATTR_FIDSZ)
		return (xattr_dir_vget(vfsp, vpp, fidp));

	return (*(vfsp)->vfs_op->vfs_vget)(vfsp, vpp, fidp);
}

int
fsop_mountroot(vfs_t *vfsp, enum whymountroot reason)
{
	return (*(vfsp)->vfs_op->vfs_mountroot)(vfsp, reason);
}

void
fsop_freefs(vfs_t *vfsp)
{
	(*(vfsp)->vfs_op->vfs_freevfs)(vfsp);
}

int
fsop_vnstate(vfs_t *vfsp, vnode_t *vp, vntrans_t nstate)
{
	return ((*(vfsp)->vfs_op->vfs_vnstate)(vfsp, vp, nstate));
}

int
fsop_sync_by_kind(int fstype, short flag, cred_t *cr)
{
	ASSERT((fstype >= 0) && (fstype < nfstype));

	if (ALLOCATED_VFSSW(&vfssw[fstype]) && VFS_INSTALLED(&vfssw[fstype]))
		return (*vfssw[fstype].vsw_vfsops.vfs_sync) (NULL, flag, cr);
	else
		return (ENOTSUP);
}

/*
 * File system initialization.  vfs_setfsops() must be called from a file
 * system's init routine.
 */

static int
fs_copyfsops(const fs_operation_def_t *template, vfsops_t *actual,
    int *unused_ops)
{
	static const fs_operation_trans_def_t vfs_ops_table[] = {
		VFSNAME_MOUNT, offsetof(vfsops_t, vfs_mount),
			fs_nosys, fs_nosys,

		VFSNAME_UNMOUNT, offsetof(vfsops_t, vfs_unmount),
			fs_nosys, fs_nosys,

		VFSNAME_ROOT, offsetof(vfsops_t, vfs_root),
			fs_nosys, fs_nosys,

		VFSNAME_STATVFS, offsetof(vfsops_t, vfs_statvfs),
			fs_nosys, fs_nosys,

		VFSNAME_SYNC, offsetof(vfsops_t, vfs_sync),
			(fs_generic_func_p) fs_sync,
			(fs_generic_func_p) fs_sync,	/* No errors allowed */

		VFSNAME_VGET, offsetof(vfsops_t, vfs_vget),
			fs_nosys, fs_nosys,

		VFSNAME_MOUNTROOT, offsetof(vfsops_t, vfs_mountroot),
			fs_nosys, fs_nosys,

		VFSNAME_FREEVFS, offsetof(vfsops_t, vfs_freevfs),
			(fs_generic_func_p)fs_freevfs,
			(fs_generic_func_p)fs_freevfs,	/* Shouldn't fail */

		VFSNAME_VNSTATE, offsetof(vfsops_t, vfs_vnstate),
			(fs_generic_func_p)fs_nosys,
			(fs_generic_func_p)fs_nosys,

		NULL, 0, NULL, NULL
	};

	return (fs_build_vector(actual, unused_ops, vfs_ops_table, template));
}

void
zfs_boot_init() {

	if (strcmp(rootfs.bo_fstype, MNTTYPE_ZFS) == 0)
		spa_boot_init();
}

int
vfs_setfsops(int fstype, const fs_operation_def_t *template, vfsops_t **actual)
{
	int error;
	int unused_ops;

	/*
	 * Verify that fstype refers to a valid fs.  Note that
	 * 0 is valid since it's used to set "stray" ops.
	 */
	if ((fstype < 0) || (fstype >= nfstype))
		return (EINVAL);

	if (!ALLOCATED_VFSSW(&vfssw[fstype]))
		return (EINVAL);

	/* Set up the operations vector. */

	error = fs_copyfsops(template, &vfssw[fstype].vsw_vfsops, &unused_ops);

	if (error != 0)
		return (error);

	vfssw[fstype].vsw_flag |= VSW_INSTALLED;

	if (actual != NULL)
		*actual = &vfssw[fstype].vsw_vfsops;

#if DEBUG
	if (unused_ops != 0)
		cmn_err(CE_WARN, "vfs_setfsops: %s: %d operations supplied "
		    "but not used", vfssw[fstype].vsw_name, unused_ops);
#endif

	return (0);
}

int
vfs_makefsops(const fs_operation_def_t *template, vfsops_t **actual)
{
	int error;
	int unused_ops;

	*actual = (vfsops_t *)kmem_alloc(sizeof (vfsops_t), KM_SLEEP);

	error = fs_copyfsops(template, *actual, &unused_ops);
	if (error != 0) {
		kmem_free(*actual, sizeof (vfsops_t));
		*actual = NULL;
		return (error);
	}

	return (0);
}

/*
 * Free a vfsops structure created as a result of vfs_makefsops().
 * NOTE: For a vfsops structure initialized by vfs_setfsops(), use
 * vfs_freevfsops_by_type().
 */
void
vfs_freevfsops(vfsops_t *vfsops)
{
	kmem_free(vfsops, sizeof (vfsops_t));
}

/*
 * Since the vfsops structure is part of the vfssw table and wasn't
 * really allocated, we're not really freeing anything.  We keep
 * the name for consistency with vfs_freevfsops().  We do, however,
 * need to take care of a little bookkeeping.
 * NOTE: For a vfsops structure created by vfs_setfsops(), use
 * vfs_freevfsops_by_type().
 */
int
vfs_freevfsops_by_type(int fstype)
{

	/* Verify that fstype refers to a loaded fs (and not fsid 0). */
	if ((fstype <= 0) || (fstype >= nfstype))
		return (EINVAL);

	WLOCK_VFSSW();
	if ((vfssw[fstype].vsw_flag & VSW_INSTALLED) == 0) {
		WUNLOCK_VFSSW();
		return (EINVAL);
	}

	vfssw[fstype].vsw_flag &= ~VSW_INSTALLED;
	WUNLOCK_VFSSW();

	return (0);
}

/* Support routines used to reference vfs_op */

/* Set the operations vector for a vfs */
void
vfs_setops(vfs_t *vfsp, vfsops_t *vfsops)
{
	vfsops_t	*op;

	ASSERT(vfsp != NULL);
	ASSERT(vfsops != NULL);

	op = vfsp->vfs_op;
	membar_consumer();
	if (vfsp->vfs_femhead == NULL &&
	    atomic_cas_ptr(&vfsp->vfs_op, op, vfsops) == op) {
		return;
	}
	fsem_setvfsops(vfsp, vfsops);
}

/* Retrieve the operations vector for a vfs */
vfsops_t *
vfs_getops(vfs_t *vfsp)
{
	vfsops_t	*op;

	ASSERT(vfsp != NULL);

	op = vfsp->vfs_op;
	membar_consumer();
	if (vfsp->vfs_femhead == NULL && op == vfsp->vfs_op) {
		return (op);
	} else {
		return (fsem_getvfsops(vfsp));
	}
}

/*
 * Returns non-zero (1) if the vfsops matches that of the vfs.
 * Returns zero (0) if not.
 */
int
vfs_matchops(vfs_t *vfsp, vfsops_t *vfsops)
{
	return (vfs_getops(vfsp) == vfsops);
}

/*
 * Returns non-zero (1) if the file system has installed a non-default,
 * non-error vfs_sync routine.  Returns zero (0) otherwise.
 */
int
vfs_can_sync(vfs_t *vfsp)
{
	/* vfs_sync() routine is not the default/error function */
	return (vfs_getops(vfsp)->vfs_sync != fs_sync);
}

/*
 * Initialize a vfs structure.
 */
void
vfs_init(vfs_t *vfsp, vfsops_t *op, void *data)
{
	/* Other initialization has been moved to vfs_alloc() */
	vfsp->vfs_count = 0;
	vfsp->vfs_next = vfsp;
	vfsp->vfs_prev = vfsp;
	vfsp->vfs_zone_next = vfsp;
	vfsp->vfs_zone_prev = vfsp;
	vfsp->vfs_lofi_minor = 0;
	sema_init(&vfsp->vfs_reflock, 1, NULL, SEMA_DEFAULT, NULL);
	vfsimpl_setup(vfsp);
	vfsp->vfs_data = (data);
	vfs_setops((vfsp), (op));
}

/*
 * Allocate and initialize the vfs implementation private data
 * structure, vfs_impl_t.
 */
void
vfsimpl_setup(vfs_t *vfsp)
{
	int i;

	if (vfsp->vfs_implp != NULL) {
		return;
	}

	vfsp->vfs_implp = kmem_alloc(sizeof (vfs_impl_t), KM_SLEEP);
	/* Note that these are #define'd in vfs.h */
	vfsp->vfs_vskap = NULL;
	vfsp->vfs_fstypevsp = NULL;

	/* Set size of counted array, then zero the array */
	vfsp->vfs_featureset[0] = VFS_FEATURE_MAXSZ - 1;
	for (i = 1; i <  VFS_FEATURE_MAXSZ; i++) {
		vfsp->vfs_featureset[i] = 0;
	}
}

/*
 * Release the vfs_impl_t structure, if it exists. Some unbundled
 * filesystems may not use the newer version of vfs and thus
 * would not contain this implementation private data structure.
 */
void
vfsimpl_teardown(vfs_t *vfsp)
{
	vfs_impl_t	*vip = vfsp->vfs_implp;

	if (vip == NULL)
		return;

	kmem_free(vfsp->vfs_implp, sizeof (vfs_impl_t));
	vfsp->vfs_implp = NULL;
}

/*
 * VFS system calls: mount, umount, syssync, statfs, fstatfs, statvfs,
 * fstatvfs, and sysfs moved to common/syscall.
 */

/*
 * Update every mounted file system.  We call the vfs_sync operation of
 * each file system type, passing it a NULL vfsp to indicate that all
 * mounted file systems of that type should be updated.
 */
void
vfs_sync(int flag)
{
	struct vfssw *vswp;
	RLOCK_VFSSW();
	for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++) {
		if (ALLOCATED_VFSSW(vswp) && VFS_INSTALLED(vswp)) {
			vfs_refvfssw(vswp);
			RUNLOCK_VFSSW();
			(void) (*vswp->vsw_vfsops.vfs_sync)(NULL, flag,
			    CRED());
			vfs_unrefvfssw(vswp);
			RLOCK_VFSSW();
		}
	}
	RUNLOCK_VFSSW();
}

void
sync(void)
{
	vfs_sync(0);
}

/*
 * compare function for vfs_by_dev avl tree. compare dev first, then mntix
 */
static int
vfs_cmp_dev(const void *aa, const void *bb)
{
	const vfs_t *a = aa;
	const vfs_t *b = bb;

	if (a->vfs_dev < b->vfs_dev)
		return (-1);
	if (a->vfs_dev > b->vfs_dev)
		return (1);
	if (a->vfs_mntix < b->vfs_mntix)
		return (-1);
	if (a->vfs_mntix > b->vfs_mntix)
		return (1);
	return (0);
}

/*
 * compare function for vfs_by_mntpnt avl tree. compare mntpnt first, then mntix
 */
static int
vfs_cmp_mntpnt(const void *aa, const void *bb)
{
	const vfs_t *a = aa;
	const vfs_t *b = bb;
	int ret;

	ret = strcmp(refstr_value(a->vfs_mntpt), refstr_value(b->vfs_mntpt));
	if (ret < 0)
		return (-1);
	if (ret > 0)
		return (1);
	if (a->vfs_mntix < b->vfs_mntix)
		return (-1);
	if (a->vfs_mntix > b->vfs_mntix)
		return (1);
	return (0);
}

/*
 * External routines.
 */

krwlock_t vfssw_lock;	/* lock accesses to vfssw */

/*
 * Lock for accessing the vfs linked list.  Initialized in vfs_mountroot(),
 * but otherwise should be accessed only via vfs_list_lock() and
 * vfs_list_unlock().  Also used to protect the timestamp for mods to the list.
 */
static krwlock_t vfslist;

/*
 * Mount devfs on /devices. This is done right after root is mounted
 * to provide device access support for the system
 */
static void
vfs_mountdevices(void)
{
	struct vfssw *vsw;
	struct vnode *mvp;
	struct mounta mounta = {	/* fake mounta for devfs_mount() */
		NULL,
		NULL,
		MS_SYSSPACE,
		NULL,
		NULL,
		0,
		NULL,
		0
	};

	/*
	 * _init devfs module to fill in the vfssw
	 */
	if (modload("fs", "devfs") == -1)
		panic("Cannot _init devfs module");

	/*
	 * Hold vfs
	 */
	RLOCK_VFSSW();
	vsw = vfs_getvfsswbyname("devfs");
	VFS_INIT(&devices, &vsw->vsw_vfsops, NULL);
	VFS_HOLD(&devices);

	/*
	 * Locate mount point
	 */
	if (lookupname("/devices", UIO_SYSSPACE, FOLLOW, NULLVPP, &mvp))
		panic("Cannot find /devices");

	/*
	 * Perform the mount of /devices
	 */
	if (VFS_MOUNT(&devices, mvp, &mounta, CRED()))
		panic("Cannot mount /devices");

	RUNLOCK_VFSSW();

	/*
	 * Set appropriate members and add to vfs list for mnttab display
	 */
	vfs_setresource(&devices, "/devices", 0);
	vfs_setmntpoint(&devices, "/devices", 0);

	/*
	 * Hold the root of /devices so it won't go away
	 */
	if (VFS_ROOT(&devices, &devicesdir))
		panic("vfs_mountdevices: not devices root");

	if (vfs_lock(&devices) != 0) {
		VN_RELE(devicesdir);
		cmn_err(CE_NOTE, "Cannot acquire vfs_lock of /devices");
		return;
	}

	if (vn_vfswlock(mvp) != 0) {
		vfs_unlock(&devices);
		VN_RELE(devicesdir);
		cmn_err(CE_NOTE, "Cannot acquire vfswlock of /devices");
		return;
	}

	vfs_add(mvp, &devices, 0);
	vn_vfsunlock(mvp);
	vfs_unlock(&devices);
	VN_RELE(devicesdir);
}

/*
 * mount the first instance of /dev  to root and remain mounted
 */
static void
vfs_mountdev1(void)
{
	struct vfssw *vsw;
	struct vnode *mvp;
	struct mounta mounta = {	/* fake mounta for sdev_mount() */
		NULL,
		NULL,
		MS_SYSSPACE | MS_OVERLAY,
		NULL,
		NULL,
		0,
		NULL,
		0
	};

	/*
	 * _init dev module to fill in the vfssw
	 */
	if (modload("fs", "dev") == -1)
		cmn_err(CE_PANIC, "Cannot _init dev module\n");

	/*
	 * Hold vfs
	 */
	RLOCK_VFSSW();
	vsw = vfs_getvfsswbyname("dev");
	VFS_INIT(&dev, &vsw->vsw_vfsops, NULL);
	VFS_HOLD(&dev);

	/*
	 * Locate mount point
	 */
	if (lookupname("/dev", UIO_SYSSPACE, FOLLOW, NULLVPP, &mvp))
		cmn_err(CE_PANIC, "Cannot find /dev\n");

	/*
	 * Perform the mount of /dev
	 */
	if (VFS_MOUNT(&dev, mvp, &mounta, CRED()))
		cmn_err(CE_PANIC, "Cannot mount /dev 1\n");

	RUNLOCK_VFSSW();

	/*
	 * Set appropriate members and add to vfs list for mnttab display
	 */
	vfs_setresource(&dev, "/dev", 0);
	vfs_setmntpoint(&dev, "/dev", 0);

	/*
	 * Hold the root of /dev so it won't go away
	 */
	if (VFS_ROOT(&dev, &devdir))
		cmn_err(CE_PANIC, "vfs_mountdev1: not dev root");

	if (vfs_lock(&dev) != 0) {
		VN_RELE(devdir);
		cmn_err(CE_NOTE, "Cannot acquire vfs_lock of /dev");
		return;
	}

	if (vn_vfswlock(mvp) != 0) {
		vfs_unlock(&dev);
		VN_RELE(devdir);
		cmn_err(CE_NOTE, "Cannot acquire vfswlock of /dev");
		return;
	}

	vfs_add(mvp, &dev, 0);
	vn_vfsunlock(mvp);
	vfs_unlock(&dev);
	VN_RELE(devdir);
}

/*
 * Mount required filesystem. This is done right after root is mounted.
 */
static void
vfs_mountfs(char *module, char *spec, char *path)
{
	struct vnode *mvp;
	struct mounta mounta;
	vfs_t *vfsp;

	bzero(&mounta, sizeof (mounta));
	mounta.flags = MS_SYSSPACE | MS_DATA;
	mounta.fstype = module;
	mounta.spec = spec;
	mounta.dir = path;
	if (lookupname(path, UIO_SYSSPACE, FOLLOW, NULLVPP, &mvp)) {
		cmn_err(CE_WARN, "Cannot find %s", path);
		return;
	}
	if (domount(NULL, &mounta, mvp, CRED(), &vfsp))
		cmn_err(CE_WARN, "Cannot mount %s", path);
	else
		VFS_RELE(vfsp);
	VN_RELE(mvp);
}

/*
 * vfs_mountroot is called by main() to mount the root filesystem.
 */
void
vfs_mountroot(void)
{
	struct vnode	*rvp = NULL;
	char		*path;
	size_t		plen;
	struct vfssw	*vswp;
	proc_t		*p;

	rw_init(&vfssw_lock, NULL, RW_DEFAULT, NULL);
	rw_init(&vfslist, NULL, RW_DEFAULT, NULL);

	/*
	 * Alloc the avl trees for quick indexing via dev and mountpoint
	 */
	avl_create(&vfs_by_dev, vfs_cmp_dev, sizeof(vfs_t),
	    offsetof(vfs_t, vfs_avldev));
	avl_create(&vfs_by_mntpnt, vfs_cmp_mntpnt, sizeof(vfs_t),
	    offsetof(vfs_t, vfs_avlmntpnt));

	/*
	 * Alloc the vfs hash bucket array and locks
	 */
	rvfs_list = kmem_zalloc(vfshsz * sizeof (rvfs_t), KM_SLEEP);

	/*
	 * Call machine-dependent routine "rootconf" to choose a root
	 * file system type.
	 */
	if (rootconf())
		panic("vfs_mountroot: cannot mount root");
	/*
	 * Get vnode for '/'.  Set up rootdir, u.u_rdir and u.u_cdir
	 * to point to it.  These are used by lookuppn() so that it
	 * knows where to start from ('/' or '.').
	 */
	vfs_setmntpoint(rootvfs, "/", 0);
	if (VFS_ROOT(rootvfs, &rootdir))
		panic("vfs_mountroot: no root vnode");

	/*
	 * At this point, the process tree consists of p0 and possibly some
	 * direct children of p0.  (i.e. there are no grandchildren)
	 *
	 * Walk through them all, setting their current directory.
	 */
	mutex_enter(&pidlock);
	for (p = practive; p != NULL; p = p->p_next) {
		ASSERT(p == &p0 || p->p_parent == &p0);

		PTOU(p)->u_cdir = rootdir;
		VN_HOLD(PTOU(p)->u_cdir);
		PTOU(p)->u_rdir = NULL;
	}
	mutex_exit(&pidlock);

	/*
	 * Setup the global zone's rootvp, now that it exists.
	 */
	global_zone->zone_rootvp = rootdir;
	VN_HOLD(global_zone->zone_rootvp);

	/*
	 * Notify the module code that it can begin using the
	 * root filesystem instead of the boot program's services.
	 */
	modrootloaded = 1;

	/*
	 * Special handling for a ZFS root file system.
	 */
	zfs_boot_init();

	/*
	 * Set up mnttab information for root
	 */
	vfs_setresource(rootvfs, rootfs.bo_name, 0);

	/*
	 * Notify cluster software that the root filesystem is available.
	 */
	clboot_mountroot();

	/* Now that we're all done with the root FS, set up its vopstats */
	if ((vswp = vfs_getvfsswbyvfsops(vfs_getops(rootvfs))) != NULL) {
		/* Set flag for statistics collection */
		if (vswp->vsw_flag & VSW_STATS) {
			initialize_vopstats(&rootvfs->vfs_vopstats);
			rootvfs->vfs_flag |= VFS_STATS;
			rootvfs->vfs_fstypevsp =
			    get_fstype_vopstats(rootvfs, vswp);
			rootvfs->vfs_vskap = get_vskstat_anchor(rootvfs);
		}
		vfs_unrefvfssw(vswp);
	}

	/*
	 * Mount /devices, /dev instance 1, /system/contract, /etc/mnttab,
	 * /etc/svc/volatile, /etc/dfs/sharetab, /system/object, and /proc.
	 */
	vfs_mountdevices();
	vfs_mountdev1();

	vfs_mountfs("ctfs", "ctfs", CTFS_ROOT);
	vfs_mountfs("proc", "/proc", "/proc");
	vfs_mountfs("mntfs", "/etc/mnttab", "/etc/mnttab");
	vfs_mountfs("tmpfs", "/etc/svc/volatile", "/etc/svc/volatile");
	vfs_mountfs("objfs", "objfs", OBJFS_ROOT);
	vfs_mountfs("bootfs", "bootfs", "/system/boot");

	if (getzoneid() == GLOBAL_ZONEID) {
		vfs_mountfs("sharefs", "sharefs", "/etc/dfs/sharetab");
	}

	if (strcmp(rootfs.bo_fstype, "zfs") != 0) {
		/*
		 * Look up the root device via devfs so that a dv_node is
		 * created for it. The vnode is never VN_RELE()ed.
		 * We allocate more than MAXPATHLEN so that the
		 * buffer passed to i_ddi_prompath_to_devfspath() is
		 * exactly MAXPATHLEN (the function expects a buffer
		 * of that length).
		 */
		plen = strlen("/devices");
		path = kmem_alloc(plen + MAXPATHLEN, KM_SLEEP);
		(void) strcpy(path, "/devices");

		if (i_ddi_prompath_to_devfspath(rootfs.bo_name, path + plen)
		    != DDI_SUCCESS ||
		    lookupname(path, UIO_SYSSPACE, FOLLOW, NULLVPP, &rvp)) {

			/* NUL terminate in case "path" has garbage */
			path[plen + MAXPATHLEN - 1] = '\0';
#ifdef	DEBUG
			cmn_err(CE_WARN, "!Cannot lookup root device: %s",
			    path);
#endif
		}
		kmem_free(path, plen + MAXPATHLEN);
	}

	vfs_mnttabvp_setup();
}

/*
 * Check to see if our "block device" is actually a file.  If so,
 * automatically add a lofi device, and keep track of this fact.
 */
static int
lofi_add(const char *fsname, struct vfs *vfsp,
    mntopts_t *mntopts, struct mounta *uap)
{
	int fromspace = (uap->flags & MS_SYSSPACE) ?
	    UIO_SYSSPACE : UIO_USERSPACE;
	struct lofi_ioctl *li = NULL;
	struct vnode *vp = NULL;
	struct pathname	pn = { NULL };
	ldi_ident_t ldi_id;
	ldi_handle_t ldi_hdl;
	vfssw_t *vfssw;
	int minor;
	int err = 0;

	if ((vfssw = vfs_getvfssw(fsname)) == NULL)
		return (0);

	if (!(vfssw->vsw_flag & VSW_CANLOFI)) {
		vfs_unrefvfssw(vfssw);
		return (0);
	}

	vfs_unrefvfssw(vfssw);
	vfssw = NULL;

	if (pn_get(uap->spec, fromspace, &pn) != 0)
		return (0);

	if (lookupname(uap->spec, fromspace, FOLLOW, NULL, &vp) != 0)
		goto out;

	if (vp->v_type != VREG)
		goto out;

	/* OK, this is a lofi mount. */

	if ((uap->flags & (MS_REMOUNT|MS_GLOBAL)) ||
	    vfs_optionisset_nolock(mntopts, MNTOPT_SUID, NULL) ||
	    vfs_optionisset_nolock(mntopts, MNTOPT_SETUID, NULL) ||
	    vfs_optionisset_nolock(mntopts, MNTOPT_DEVICES, NULL)) {
		err = EINVAL;
		goto out;
	}

	ldi_id = ldi_ident_from_anon();
	li = kmem_zalloc(sizeof (*li), KM_SLEEP);
	(void) strlcpy(li->li_filename, pn.pn_path, MAXPATHLEN);

	err = ldi_open_by_name("/dev/lofictl", FREAD | FWRITE, kcred,
	    &ldi_hdl, ldi_id);

	if (err)
		goto out2;

	err = ldi_ioctl(ldi_hdl, LOFI_MAP_FILE, (intptr_t)li,
	    FREAD | FWRITE | FKIOCTL, kcred, &minor);

	(void) ldi_close(ldi_hdl, FREAD | FWRITE, kcred);

	if (!err)
		vfsp->vfs_lofi_minor = minor;

out2:
	ldi_ident_release(ldi_id);
out:
	if (li != NULL)
		kmem_free(li, sizeof (*li));
	if (vp != NULL)
		VN_RELE(vp);
	pn_free(&pn);
	return (err);
}

static void
lofi_remove(struct vfs *vfsp)
{
	struct lofi_ioctl *li = NULL;
	ldi_ident_t ldi_id;
	ldi_handle_t ldi_hdl;
	int err;

	if (vfsp->vfs_lofi_minor == 0)
		return;

	ldi_id = ldi_ident_from_anon();

	li = kmem_zalloc(sizeof (*li), KM_SLEEP);
	li->li_minor = vfsp->vfs_lofi_minor;
	li->li_cleanup = B_TRUE;

	err = ldi_open_by_name("/dev/lofictl", FREAD | FWRITE, kcred,
	    &ldi_hdl, ldi_id);

	if (err)
		goto out;

	err = ldi_ioctl(ldi_hdl, LOFI_UNMAP_FILE_MINOR, (intptr_t)li,
	    FREAD | FWRITE | FKIOCTL, kcred, NULL);

	(void) ldi_close(ldi_hdl, FREAD | FWRITE, kcred);

	if (!err)
		vfsp->vfs_lofi_minor = 0;

out:
	ldi_ident_release(ldi_id);
	if (li != NULL)
		kmem_free(li, sizeof (*li));
}

/*
 * Common mount code.  Called from the system call entry point, from autofs,
 * nfsv4 trigger mounts, and from pxfs.
 *
 * Takes the effective file system type, mount arguments, the mount point
 * vnode, flags specifying whether the mount is a remount and whether it
 * should be entered into the vfs list, and credentials.  Fills in its vfspp
 * parameter with the mounted file system instance's vfs.
 *
 * Note that the effective file system type is specified as a string.  It may
 * be null, in which case it's determined from the mount arguments, and may
 * differ from the type specified in the mount arguments; this is a hook to
 * allow interposition when instantiating file system instances.
 *
 * The caller is responsible for releasing its own hold on the mount point
 * vp (this routine does its own hold when necessary).
 * Also note that for remounts, the mount point vp should be the vnode for
 * the root of the file system rather than the vnode that the file system
 * is mounted on top of.
 */
int
domount(char *fsname, struct mounta *uap, vnode_t *vp, struct cred *credp,
	struct vfs **vfspp)
{
	struct vfssw	*vswp;
	vfsops_t	*vfsops;
	struct vfs	*vfsp;
	struct vnode	*bvp;
	dev_t		bdev = 0;
	mntopts_t	mnt_mntopts;
	int		error = 0;
	int		copyout_error = 0;
	int		ovflags;
	char		*opts = uap->optptr;
	char		*inargs = opts;
	int		optlen = uap->optlen;
	int		remount;
	int		rdonly;
	int		nbmand = 0;
	int		delmip = 0;
	int		addmip = 0;
	int		splice = ((uap->flags & MS_NOSPLICE) == 0);
	int		fromspace = (uap->flags & MS_SYSSPACE) ?
	    UIO_SYSSPACE : UIO_USERSPACE;
	char		*resource = NULL, *mountpt = NULL;
	refstr_t	*oldresource, *oldmntpt;
	struct pathname	pn, rpn;
	vsk_anchor_t	*vskap;
	char fstname[FSTYPSZ];
	zone_t		*zone;

	/*
	 * The v_flag value for the mount point vp is permanently set
	 * to VVFSLOCK so that no one bypasses the vn_vfs*locks routine
	 * for mount point locking.
	 */
	mutex_enter(&vp->v_lock);
	vp->v_flag |= VVFSLOCK;
	mutex_exit(&vp->v_lock);

	mnt_mntopts.mo_count = 0;
	/*
	 * Find the ops vector to use to invoke the file system-specific mount
	 * method.  If the fsname argument is non-NULL, use it directly.
	 * Otherwise, dig the file system type information out of the mount
	 * arguments.
	 *
	 * A side effect is to hold the vfssw entry.
	 *
	 * Mount arguments can be specified in several ways, which are
	 * distinguished by flag bit settings.  The preferred way is to set
	 * MS_OPTIONSTR, indicating an 8 argument mount with the file system
	 * type supplied as a character string and the last two arguments
	 * being a pointer to a character buffer and the size of the buffer.
	 * On entry, the buffer holds a null terminated list of options; on
	 * return, the string is the list of options the file system
	 * recognized. If MS_DATA is set arguments five and six point to a
	 * block of binary data which the file system interprets.
	 * A further wrinkle is that some callers don't set MS_FSS and MS_DATA
	 * consistently with these conventions.  To handle them, we check to
	 * see whether the pointer to the file system name has a numeric value
	 * less than 256.  If so, we treat it as an index.
	 */
	if (fsname != NULL) {
		if ((vswp = vfs_getvfssw(fsname)) == NULL) {
			return (EINVAL);
		}
	} else if (uap->flags & (MS_OPTIONSTR | MS_DATA | MS_FSS)) {
		size_t n;
		uint_t fstype;

		fsname = fstname;

		if ((fstype = (uintptr_t)uap->fstype) < 256) {
			RLOCK_VFSSW();
			if (fstype == 0 || fstype >= nfstype ||
			    !ALLOCATED_VFSSW(&vfssw[fstype])) {
				RUNLOCK_VFSSW();
				return (EINVAL);
			}
			(void) strcpy(fsname, vfssw[fstype].vsw_name);
			RUNLOCK_VFSSW();
			if ((vswp = vfs_getvfssw(fsname)) == NULL)
				return (EINVAL);
		} else {
			/*
			 * Handle either kernel or user address space.
			 */
			if (uap->flags & MS_SYSSPACE) {
				error = copystr(uap->fstype, fsname,
				    FSTYPSZ, &n);
			} else {
				error = copyinstr(uap->fstype, fsname,
				    FSTYPSZ, &n);
			}
			if (error) {
				if (error == ENAMETOOLONG)
					return (EINVAL);
				return (error);
			}
			if ((vswp = vfs_getvfssw(fsname)) == NULL)
				return (EINVAL);
		}
	} else {
		if ((vswp = vfs_getvfsswbyvfsops(vfs_getops(rootvfs))) == NULL)
			return (EINVAL);
		fsname = vswp->vsw_name;
	}
	if (!VFS_INSTALLED(vswp))
		return (EINVAL);

	if ((error = secpolicy_fs_allowed_mount(fsname)) != 0)  {
		vfs_unrefvfssw(vswp);
		return (error);
	}

	vfsops = &vswp->vsw_vfsops;

	vfs_copyopttbl(&vswp->vsw_optproto, &mnt_mntopts);
	/*
	 * Fetch mount options and parse them for generic vfs options
	 */
	if (uap->flags & MS_OPTIONSTR) {
		/*
		 * Limit the buffer size
		 */
		if (optlen < 0 || optlen > MAX_MNTOPT_STR) {
			error = EINVAL;
			goto errout;
		}
		if ((uap->flags & MS_SYSSPACE) == 0) {
			inargs = kmem_alloc(MAX_MNTOPT_STR, KM_SLEEP);
			inargs[0] = '\0';
			if (optlen) {
				error = copyinstr(opts, inargs, (size_t)optlen,
				    NULL);
				if (error) {
					goto errout;
				}
			}
		}
		vfs_parsemntopts(&mnt_mntopts, inargs, 0);
	}
	/*
	 * Flag bits override the options string.
	 */
	if (uap->flags & MS_REMOUNT)
		vfs_setmntopt_nolock(&mnt_mntopts, MNTOPT_REMOUNT, NULL, 0, 0);
	if (uap->flags & MS_RDONLY)
		vfs_setmntopt_nolock(&mnt_mntopts, MNTOPT_RO, NULL, 0, 0);
	if (uap->flags & MS_NOSUID)
		vfs_setmntopt_nolock(&mnt_mntopts, MNTOPT_NOSUID, NULL, 0, 0);

	/*
	 * Check if this is a remount; must be set in the option string and
	 * the file system must support a remount option.
	 */
	if (remount = vfs_optionisset_nolock(&mnt_mntopts,
	    MNTOPT_REMOUNT, NULL)) {
		if (!(vswp->vsw_flag & VSW_CANREMOUNT)) {
			error = ENOTSUP;
			goto errout;
		}
		uap->flags |= MS_REMOUNT;
	}

	/*
	 * uap->flags and vfs_optionisset() should agree.
	 */
	if (rdonly = vfs_optionisset_nolock(&mnt_mntopts, MNTOPT_RO, NULL)) {
		uap->flags |= MS_RDONLY;
	}
	if (vfs_optionisset_nolock(&mnt_mntopts, MNTOPT_NOSUID, NULL)) {
		uap->flags |= MS_NOSUID;
	}
	nbmand = vfs_optionisset_nolock(&mnt_mntopts, MNTOPT_NBMAND, NULL);
	ASSERT(splice || !remount);
	/*
	 * If we are splicing the fs into the namespace,
	 * perform mount point checks.
	 *
	 * We want to resolve the path for the mount point to eliminate
	 * '.' and ".." and symlinks in mount points; we can't do the
	 * same for the resource string, since it would turn
	 * "/dev/dsk/c0t0d0s0" into "/devices/pci@...".  We need to do
	 * this before grabbing vn_vfswlock(), because otherwise we
	 * would deadlock with lookuppn().
	 */
	if (splice) {
		ASSERT(vp->v_count > 0);

		/*
		 * Pick up mount point and device from appropriate space.
		 */
		if (pn_get(uap->spec, fromspace, &pn) == 0) {
			resource = kmem_alloc(pn.pn_pathlen + 1,
			    KM_SLEEP);
			(void) strcpy(resource, pn.pn_path);
			pn_free(&pn);
		}
		/*
		 * Do a lookupname prior to taking the
		 * writelock. Mark this as completed if
		 * successful for later cleanup and addition to
		 * the mount in progress table.
		 */
		if ((uap->flags & MS_GLOBAL) == 0 &&
		    lookupname(uap->spec, fromspace,
		    FOLLOW, NULL, &bvp) == 0) {
			addmip = 1;
		}

		if ((error = pn_get(uap->dir, fromspace, &pn)) == 0) {
			pathname_t *pnp;

			if (*pn.pn_path != '/') {
				error = EINVAL;
				pn_free(&pn);
				goto errout;
			}
			pn_alloc(&rpn);
			/*
			 * Kludge to prevent autofs from deadlocking with
			 * itself when it calls domount().
			 *
			 * If autofs is calling, it is because it is doing
			 * (autofs) mounts in the process of an NFS mount.  A
			 * lookuppn() here would cause us to block waiting for
			 * said NFS mount to complete, which can't since this
			 * is the thread that was supposed to doing it.
			 */
			if (fromspace == UIO_USERSPACE) {
				if ((error = lookuppn(&pn, &rpn, FOLLOW, NULL,
				    NULL)) == 0) {
					pnp = &rpn;
				} else {
					/*
					 * The file disappeared or otherwise
					 * became inaccessible since we opened
					 * it; might as well fail the mount
					 * since the mount point is no longer
					 * accessible.
					 */
					pn_free(&rpn);
					pn_free(&pn);
					goto errout;
				}
			} else {
				pnp = &pn;
			}
			mountpt = kmem_alloc(pnp->pn_pathlen + 1, KM_SLEEP);
			(void) strcpy(mountpt, pnp->pn_path);

			/*
			 * If the addition of the zone's rootpath
			 * would push us over a total path length
			 * of MAXPATHLEN, we fail the mount with
			 * ENAMETOOLONG, which is what we would have
			 * gotten if we were trying to perform the same
			 * mount in the global zone.
			 *
			 * strlen() doesn't count the trailing
			 * '\0', but zone_rootpathlen counts both a
			 * trailing '/' and the terminating '\0'.
			 */
			if ((curproc->p_zone->zone_rootpathlen - 1 +
			    strlen(mountpt)) > MAXPATHLEN ||
			    (resource != NULL &&
			    (curproc->p_zone->zone_rootpathlen - 1 +
			    strlen(resource)) > MAXPATHLEN)) {
				error = ENAMETOOLONG;
			}

			pn_free(&rpn);
			pn_free(&pn);
		}

		if (error)
			goto errout;

		/*
		 * Prevent path name resolution from proceeding past
		 * the mount point.
		 */
		if (vn_vfswlock(vp) != 0) {
			error = EBUSY;
			goto errout;
		}

		/*
		 * Verify that it's legitimate to establish a mount on
		 * the prospective mount point.
		 */
		if (vn_mountedvfs(vp) != NULL) {
			/*
			 * The mount point lock was obtained after some
			 * other thread raced through and established a mount.
			 */
			vn_vfsunlock(vp);
			error = EBUSY;
			goto errout;
		}
		if (vp->v_flag & VNOMOUNT) {
			vn_vfsunlock(vp);
			error = EINVAL;
			goto errout;
		}
	}
	if ((uap->flags & (MS_DATA | MS_OPTIONSTR)) == 0) {
		uap->dataptr = NULL;
		uap->datalen = 0;
	}

	/*
	 * If this is a remount, we don't want to create a new VFS.
	 * Instead, we pass the existing one with a remount flag.
	 */
	if (remount) {
		/*
		 * Confirm that the mount point is the root vnode of the
		 * file system that is being remounted.
		 * This can happen if the user specifies a different
		 * mount point directory pathname in the (re)mount command.
		 *
		 * Code below can only be reached if splice is true, so it's
		 * safe to do vn_vfsunlock() here.
		 */
		if ((vp->v_flag & VROOT) == 0) {
			vn_vfsunlock(vp);
			error = ENOENT;
			goto errout;
		}
		/*
		 * Disallow making file systems read-only unless file system
		 * explicitly allows it in its vfssw.  Ignore other flags.
		 */
		if (rdonly && vn_is_readonly(vp) == 0 &&
		    (vswp->vsw_flag & VSW_CANRWRO) == 0) {
			vn_vfsunlock(vp);
			error = EINVAL;
			goto errout;
		}
		/*
		 * Disallow changing the NBMAND disposition of the file
		 * system on remounts.
		 */
		if ((nbmand && ((vp->v_vfsp->vfs_flag & VFS_NBMAND) == 0)) ||
		    (!nbmand && (vp->v_vfsp->vfs_flag & VFS_NBMAND))) {
			vn_vfsunlock(vp);
			error = EINVAL;
			goto errout;
		}
		vfsp = vp->v_vfsp;
		ovflags = vfsp->vfs_flag;
		vfsp->vfs_flag |= VFS_REMOUNT;
		vfsp->vfs_flag &= ~VFS_RDONLY;
	} else {
		vfsp = vfs_alloc(KM_SLEEP);
		VFS_INIT(vfsp, vfsops, NULL);
	}

	VFS_HOLD(vfsp);

	if ((error = lofi_add(fsname, vfsp, &mnt_mntopts, uap)) != 0) {
		if (!remount) {
			if (splice)
				vn_vfsunlock(vp);
			vfs_free(vfsp);
		} else {
			vn_vfsunlock(vp);
			VFS_RELE(vfsp);
		}
		goto errout;
	}

	/*
	 * PRIV_SYS_MOUNT doesn't mean you can become root.
	 */
	if (vfsp->vfs_lofi_minor != 0) {
		uap->flags |= MS_NOSUID;
		vfs_setmntopt_nolock(&mnt_mntopts, MNTOPT_NOSUID, NULL, 0, 0);
	}

	/*
	 * The vfs_reflock is not used anymore the code below explicitly
	 * holds it preventing others accesing it directly.
	 */
	if ((sema_tryp(&vfsp->vfs_reflock) == 0) &&
	    !(vfsp->vfs_flag & VFS_REMOUNT))
		cmn_err(CE_WARN,
		    "mount type %s couldn't get vfs_reflock", vswp->vsw_name);

	/*
	 * Lock the vfs. If this is a remount we want to avoid spurious umount
	 * failures that happen as a side-effect of fsflush() and other mount
	 * and unmount operations that might be going on simultaneously and
	 * may have locked the vfs currently. To not return EBUSY immediately
	 * here we use vfs_lock_wait() instead vfs_lock() for the remount case.
	 */
	if (!remount) {
		if (error = vfs_lock(vfsp)) {
			vfsp->vfs_flag = ovflags;

			lofi_remove(vfsp);

			if (splice)
				vn_vfsunlock(vp);
			vfs_free(vfsp);
			goto errout;
		}
	} else {
		vfs_lock_wait(vfsp);
	}

	/*
	 * Add device to mount in progress table, global mounts require special
	 * handling. It is possible that we have already done the lookupname
	 * on a spliced, non-global fs. If so, we don't want to do it again
	 * since we cannot do a lookupname after taking the
	 * wlock above. This case is for a non-spliced, non-global filesystem.
	 */
	if (!addmip) {
		if ((uap->flags & MS_GLOBAL) == 0 &&
		    lookupname(uap->spec, fromspace, FOLLOW, NULL, &bvp) == 0) {
			addmip = 1;
		}
	}

	if (addmip) {
		vnode_t *lvp = NULL;

		error = vfs_get_lofi(vfsp, &lvp);
		if (error > 0) {
			lofi_remove(vfsp);

			if (splice)
				vn_vfsunlock(vp);
			vfs_unlock(vfsp);

			if (remount) {
				VFS_RELE(vfsp);
			} else {
				vfs_free(vfsp);
			}

			goto errout;
		} else if (error == -1) {
			bdev = bvp->v_rdev;
			VN_RELE(bvp);
		} else {
			bdev = lvp->v_rdev;
			VN_RELE(lvp);
			VN_RELE(bvp);
		}

		vfs_addmip(bdev, vfsp);
		addmip = 0;
		delmip = 1;
	}
	/*
	 * Invalidate cached entry for the mount point.
	 */
	if (splice)
		dnlc_purge_vp(vp);

	/*
	 * If have an option string but the filesystem doesn't supply a
	 * prototype options table, create a table with the global
	 * options and sufficient room to accept all the options in the
	 * string.  Then parse the passed in option string
	 * accepting all the options in the string.  This gives us an
	 * option table with all the proper cancel properties for the
	 * global options.
	 *
	 * Filesystems that supply a prototype options table are handled
	 * earlier in this function.
	 */
	if (uap->flags & MS_OPTIONSTR) {
		if (!(vswp->vsw_flag & VSW_HASPROTO)) {
			mntopts_t tmp_mntopts;

			tmp_mntopts.mo_count = 0;
			vfs_createopttbl_extend(&tmp_mntopts, inargs,
			    &mnt_mntopts);
			vfs_parsemntopts(&tmp_mntopts, inargs, 1);
			vfs_swapopttbl_nolock(&mnt_mntopts, &tmp_mntopts);
			vfs_freeopttbl(&tmp_mntopts);
		}
	}

	/*
	 * Serialize with zone state transitions.
	 * See vfs_list_add; zone mounted into is:
	 * 	zone_find_by_path(refstr_value(vfsp->vfs_mntpt))
	 * not the zone doing the mount (curproc->p_zone), but if we're already
	 * inside a NGZ, then we know what zone we are.
	 */
	if (INGLOBALZONE(curproc)) {
		zone = zone_find_by_path(mountpt);
		ASSERT(zone != NULL);
	} else {
		zone = curproc->p_zone;
		/*
		 * zone_find_by_path does a hold, so do one here too so that
		 * we can do a zone_rele after mount_completed.
		 */
		zone_hold(zone);
	}
	mount_in_progress(zone);
	/*
	 * Instantiate (or reinstantiate) the file system.  If appropriate,
	 * splice it into the file system name space.
	 *
	 * We want VFS_MOUNT() to be able to override the vfs_resource
	 * string if necessary (ie, mntfs), and also for a remount to
	 * change the same (necessary when remounting '/' during boot).
	 * So we set up vfs_mntpt and vfs_resource to what we think they
	 * should be, then hand off control to VFS_MOUNT() which can
	 * override this.
	 *
	 * For safety's sake, when changing vfs_resource or vfs_mntpt of
	 * a vfs which is on the vfs list (i.e. during a remount), we must
	 * never set those fields to NULL. Several bits of code make
	 * assumptions that the fields are always valid.
	 */
	vfs_swapopttbl(&mnt_mntopts, &vfsp->vfs_mntopts);
	if (remount) {
		if ((oldresource = vfsp->vfs_resource) != NULL)
			refstr_hold(oldresource);
		if ((oldmntpt = vfsp->vfs_mntpt) != NULL)
			refstr_hold(oldmntpt);
	}
	vfs_setresource(vfsp, resource, 0);
	vfs_setmntpoint(vfsp, mountpt, 0);

	/*
	 * going to mount on this vnode, so notify.
	 */
	vnevent_mountedover(vp, NULL);
	error = VFS_MOUNT(vfsp, vp, uap, credp);

	if (uap->flags & MS_RDONLY)
		vfs_setmntopt(vfsp, MNTOPT_RO, NULL, 0);
	if (uap->flags & MS_NOSUID)
		vfs_setmntopt(vfsp, MNTOPT_NOSUID, NULL, 0);
	if (uap->flags & MS_GLOBAL)
		vfs_setmntopt(vfsp, MNTOPT_GLOBAL, NULL, 0);

	if (error) {
		lofi_remove(vfsp);

		if (remount) {
			/* put back pre-remount options */
			vfs_swapopttbl(&mnt_mntopts, &vfsp->vfs_mntopts);
			vfs_setmntpoint(vfsp, refstr_value(oldmntpt),
			    VFSSP_VERBATIM);
			if (oldmntpt)
				refstr_rele(oldmntpt);
			vfs_setresource(vfsp, refstr_value(oldresource),
			    VFSSP_VERBATIM);
			if (oldresource)
				refstr_rele(oldresource);
			vfsp->vfs_flag = ovflags;
			vfs_unlock(vfsp);
			VFS_RELE(vfsp);
		} else {
			vfs_unlock(vfsp);
			vfs_freemnttab(vfsp);
			vfs_free(vfsp);
		}
	} else {
		/*
		 * Set the mount time to now
		 */
		vfsp->vfs_mtime = ddi_get_time();
		if (remount) {
			vfsp->vfs_flag &= ~VFS_REMOUNT;
			if (oldresource)
				refstr_rele(oldresource);
			if (oldmntpt)
				refstr_rele(oldmntpt);
		} else if (splice) {
			/*
			 * Link vfsp into the name space at the mount
			 * point. Vfs_add() is responsible for
			 * holding the mount point which will be
			 * released when vfs_remove() is called.
			 */
			vfs_add(vp, vfsp, uap->flags);
		} else {
			/*
			 * Hold the reference to file system which is
			 * not linked into the name space.
			 */
			vfsp->vfs_zone = NULL;
			VFS_HOLD(vfsp);
			vfsp->vfs_vnodecovered = NULL;
		}
		/*
		 * Set flags for global options encountered
		 */
		if (vfs_optionisset(vfsp, MNTOPT_RO, NULL))
			vfsp->vfs_flag |= VFS_RDONLY;
		else
			vfsp->vfs_flag &= ~VFS_RDONLY;
		if (vfs_optionisset(vfsp, MNTOPT_NOSUID, NULL)) {
			vfsp->vfs_flag |= (VFS_NOSETUID|VFS_NODEVICES);
		} else {
			if (vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL))
				vfsp->vfs_flag |= VFS_NODEVICES;
			else
				vfsp->vfs_flag &= ~VFS_NODEVICES;
			if (vfs_optionisset(vfsp, MNTOPT_NOSETUID, NULL))
				vfsp->vfs_flag |= VFS_NOSETUID;
			else
				vfsp->vfs_flag &= ~VFS_NOSETUID;
		}
		if (vfs_optionisset(vfsp, MNTOPT_NBMAND, NULL))
			vfsp->vfs_flag |= VFS_NBMAND;
		else
			vfsp->vfs_flag &= ~VFS_NBMAND;

		if (vfs_optionisset(vfsp, MNTOPT_XATTR, NULL))
			vfsp->vfs_flag |= VFS_XATTR;
		else
			vfsp->vfs_flag &= ~VFS_XATTR;

		if (vfs_optionisset(vfsp, MNTOPT_NOEXEC, NULL))
			vfsp->vfs_flag |= VFS_NOEXEC;
		else
			vfsp->vfs_flag &= ~VFS_NOEXEC;

		/*
		 * Now construct the output option string of options
		 * we recognized.
		 */
		if (uap->flags & MS_OPTIONSTR) {
			vfs_list_read_lock();
			copyout_error = vfs_buildoptionstr(
			    &vfsp->vfs_mntopts, inargs, optlen);
			vfs_list_unlock();
			if (copyout_error == 0 &&
			    (uap->flags & MS_SYSSPACE) == 0) {
				copyout_error = copyoutstr(inargs, opts,
				    optlen, NULL);
			}
		}

		/*
		 * If this isn't a remount, set up the vopstats before
		 * anyone can touch this. We only allow spliced file
		 * systems (file systems which are in the namespace) to
		 * have the VFS_STATS flag set.
		 * NOTE: PxFS mounts the underlying file system with
		 * MS_NOSPLICE set and copies those vfs_flags to its private
		 * vfs structure. As a result, PxFS should never have
		 * the VFS_STATS flag or else we might access the vfs
		 * statistics-related fields prior to them being
		 * properly initialized.
		 */
		if (!remount && (vswp->vsw_flag & VSW_STATS) && splice) {
			initialize_vopstats(&vfsp->vfs_vopstats);
			/*
			 * We need to set vfs_vskap to NULL because there's
			 * a chance it won't be set below.  This is checked
			 * in teardown_vopstats() so we can't have garbage.
			 */
			vfsp->vfs_vskap = NULL;
			vfsp->vfs_flag |= VFS_STATS;
			vfsp->vfs_fstypevsp = get_fstype_vopstats(vfsp, vswp);
		}

		if (vswp->vsw_flag & VSW_XID)
			vfsp->vfs_flag |= VFS_XID;

		vfs_unlock(vfsp);
	}
	mount_completed(zone);
	zone_rele(zone);
	if (splice)
		vn_vfsunlock(vp);

	if ((error == 0) && (copyout_error == 0)) {
		if (!remount) {
			/*
			 * Don't call get_vskstat_anchor() while holding
			 * locks since it allocates memory and calls
			 * VFS_STATVFS().  For NFS, the latter can generate
			 * an over-the-wire call.
			 */
			vskap = get_vskstat_anchor(vfsp);
			/* Only take the lock if we have something to do */
			if (vskap != NULL) {
				vfs_lock_wait(vfsp);
				if (vfsp->vfs_flag & VFS_STATS) {
					vfsp->vfs_vskap = vskap;
				}
				vfs_unlock(vfsp);
			}
		}
		/* Return vfsp to caller. */
		*vfspp = vfsp;
	}
errout:
	vfs_freeopttbl(&mnt_mntopts);
	if (resource != NULL)
		kmem_free(resource, strlen(resource) + 1);
	if (mountpt != NULL)
		kmem_free(mountpt, strlen(mountpt) + 1);
	/*
	 * It is possible we errored prior to adding to mount in progress
	 * table. Must free vnode we acquired with successful lookupname.
	 */
	if (addmip)
		VN_RELE(bvp);
	if (delmip)
		vfs_delmip(vfsp);
	ASSERT(vswp != NULL);
	vfs_unrefvfssw(vswp);
	if (inargs != opts)
		kmem_free(inargs, MAX_MNTOPT_STR);
	if (copyout_error) {
		lofi_remove(vfsp);
		VFS_RELE(vfsp);
		error = copyout_error;
	}
	return (error);
}

static void
vfs_setpath(
    struct vfs *vfsp,		/* vfs being updated */
    refstr_t **refp,		/* Ref-count string to contain the new path */
    const char *newpath,	/* Path to add to refp (above) */
    uint32_t flag)		/* flag */
{
	size_t len;
	refstr_t *ref;
	zone_t *zone = curproc->p_zone;
	char *sp;
	int have_list_lock = 0;

	ASSERT(!VFS_ON_LIST(vfsp) || vfs_lock_held(vfsp));

	/*
	 * New path must be less than MAXPATHLEN because mntfs
	 * will only display up to MAXPATHLEN bytes. This is currently
	 * safe, because domount() uses pn_get(), and other callers
	 * similarly cap the size to fewer than MAXPATHLEN bytes.
	 */

	ASSERT(strlen(newpath) < MAXPATHLEN);

	/* mntfs requires consistency while vfs list lock is held */

	if (VFS_ON_LIST(vfsp)) {
		have_list_lock = 1;
		vfs_list_lock();
	}

	if (*refp != NULL)
		refstr_rele(*refp);

	/*
	 * If we are in a non-global zone then we prefix the supplied path,
	 * newpath, with the zone's root path, with two exceptions. The first
	 * is where we have been explicitly directed to avoid doing so; this
	 * will be the case following a failed remount, where the path supplied
	 * will be a saved version which must now be restored. The second
	 * exception is where newpath is not a pathname but a descriptive name,
	 * e.g. "procfs".
	 */
	if (zone == global_zone || (flag & VFSSP_VERBATIM) || *newpath != '/') {
		ref = refstr_alloc(newpath);
		goto out;
	}

	/*
	 * Truncate the trailing '/' in the zoneroot, and merge
	 * in the zone's rootpath with the "newpath" (resource
	 * or mountpoint) passed in.
	 *
	 * The size of the required buffer is thus the size of
	 * the buffer required for the passed-in newpath
	 * (strlen(newpath) + 1), plus the size of the buffer
	 * required to hold zone_rootpath (zone_rootpathlen)
	 * minus one for one of the now-superfluous NUL
	 * terminations, minus one for the trailing '/'.
	 *
	 * That gives us:
	 *
	 * (strlen(newpath) + 1) + zone_rootpathlen - 1 - 1
	 *
	 * Which is what we have below.
	 */

	len = strlen(newpath) + zone->zone_rootpathlen - 1;
	sp = kmem_alloc(len, KM_SLEEP);

	/*
	 * Copy everything including the trailing slash, which
	 * we then overwrite with the NUL character.
	 */

	(void) strcpy(sp, zone->zone_rootpath);
	sp[zone->zone_rootpathlen - 2] = '\0';
	(void) strcat(sp, newpath);

	ref = refstr_alloc(sp);
	kmem_free(sp, len);
out:
	*refp = ref;

	if (have_list_lock) {
		vfs_mnttab_modtimeupd();
		vfs_list_unlock();
	}
}

/*
 * Record a mounted resource name in a vfs structure.
 * If vfsp is already mounted, caller must hold the vfs lock.
 */
void
vfs_setresource(struct vfs *vfsp, const char *resource, uint32_t flag)
{
	if (resource == NULL || resource[0] == '\0')
		resource = VFS_NORESOURCE;
	vfs_setpath(vfsp, &vfsp->vfs_resource, resource, flag);
}

/*
 * Record a mount point name in a vfs structure.
 * If vfsp is already mounted, caller must hold the vfs lock.
 */
void
vfs_setmntpoint(struct vfs *vfsp, const char *mntpt, uint32_t flag)
{
	if (mntpt == NULL || mntpt[0] == '\0')
		mntpt = VFS_NOMNTPT;
	vfs_setpath(vfsp, &vfsp->vfs_mntpt, mntpt, flag);
}

/* Returns the vfs_resource. Caller must call refstr_rele() when finished. */

refstr_t *
vfs_getresource(const struct vfs *vfsp)
{
	refstr_t *resource;

	vfs_list_read_lock();
	resource = vfsp->vfs_resource;
	refstr_hold(resource);
	vfs_list_unlock();

	return (resource);
}

/* Returns the vfs_mntpt. Caller must call refstr_rele() when finished. */

refstr_t *
vfs_getmntpoint(const struct vfs *vfsp)
{
	refstr_t *mntpt;

	vfs_list_read_lock();
	mntpt = vfsp->vfs_mntpt;
	refstr_hold(mntpt);
	vfs_list_unlock();

	return (mntpt);
}

/*
 * Create an empty options table with enough empty slots to hold all
 * The options in the options string passed as an argument.
 * Potentially prepend another options table.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mops.
 */
static void
vfs_createopttbl_extend(mntopts_t *mops, const char *opts,
    const mntopts_t *mtmpl)
{
	const char *s = opts;
	uint_t count;

	if (opts == NULL || *opts == '\0') {
		count = 0;
	} else {
		count = 1;

		/*
		 * Count number of options in the string
		 */
		for (s = strchr(s, ','); s != NULL; s = strchr(s, ',')) {
			count++;
			s++;
		}
	}
	vfs_copyopttbl_extend(mtmpl, mops, count);
}

/*
 * Create an empty options table with enough empty slots to hold all
 * The options in the options string passed as an argument.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mops.
 */
void
vfs_createopttbl(mntopts_t *mops, const char *opts)
{
	vfs_createopttbl_extend(mops, opts, NULL);
}


/*
 * Swap two mount options tables
 */
static void
vfs_swapopttbl_nolock(mntopts_t *optbl1, mntopts_t *optbl2)
{
	uint_t tmpcnt;
	mntopt_t *tmplist;

	tmpcnt = optbl2->mo_count;
	tmplist = optbl2->mo_list;
	optbl2->mo_count = optbl1->mo_count;
	optbl2->mo_list = optbl1->mo_list;
	optbl1->mo_count = tmpcnt;
	optbl1->mo_list = tmplist;
}

static void
vfs_swapopttbl(mntopts_t *optbl1, mntopts_t *optbl2)
{
	vfs_list_lock();
	vfs_swapopttbl_nolock(optbl1, optbl2);
	vfs_mnttab_modtimeupd();
	vfs_list_unlock();
}

static char **
vfs_copycancelopt_extend(char **const moc, int extend)
{
	int i = 0;
	int j;
	char **result;

	if (moc != NULL) {
		for (; moc[i] != NULL; i++)
			/* count number of options to cancel */;
	}

	if (i + extend == 0)
		return (NULL);

	result = kmem_alloc((i + extend + 1) * sizeof (char *), KM_SLEEP);

	for (j = 0; j < i; j++) {
		result[j] = kmem_alloc(strlen(moc[j]) + 1, KM_SLEEP);
		(void) strcpy(result[j], moc[j]);
	}
	for (; j <= i + extend; j++)
		result[j] = NULL;

	return (result);
}

static void
vfs_copyopt(const mntopt_t *s, mntopt_t *d)
{
	char *sp, *dp;

	d->mo_flags = s->mo_flags;
	d->mo_data = s->mo_data;
	sp = s->mo_name;
	if (sp != NULL) {
		dp = kmem_alloc(strlen(sp) + 1, KM_SLEEP);
		(void) strcpy(dp, sp);
		d->mo_name = dp;
	} else {
		d->mo_name = NULL; /* should never happen */
	}

	d->mo_cancel = vfs_copycancelopt_extend(s->mo_cancel, 0);

	sp = s->mo_arg;
	if (sp != NULL) {
		dp = kmem_alloc(strlen(sp) + 1, KM_SLEEP);
		(void) strcpy(dp, sp);
		d->mo_arg = dp;
	} else {
		d->mo_arg = NULL;
	}
}

/*
 * Copy a mount options table, possibly allocating some spare
 * slots at the end.  It is permissible to copy_extend the NULL table.
 */
static void
vfs_copyopttbl_extend(const mntopts_t *smo, mntopts_t *dmo, int extra)
{
	uint_t i, count;
	mntopt_t *motbl;

	/*
	 * Clear out any existing stuff in the options table being initialized
	 */
	vfs_freeopttbl(dmo);
	count = (smo == NULL) ? 0 : smo->mo_count;
	if ((count + extra) == 0)	/* nothing to do */
		return;
	dmo->mo_count = count + extra;
	motbl = kmem_zalloc((count + extra) * sizeof (mntopt_t), KM_SLEEP);
	dmo->mo_list = motbl;
	for (i = 0; i < count; i++) {
		vfs_copyopt(&smo->mo_list[i], &motbl[i]);
	}
	for (i = count; i < count + extra; i++) {
		motbl[i].mo_flags = MO_EMPTY;
	}
}

/*
 * Copy a mount options table.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect smo and dmo.
 */
void
vfs_copyopttbl(const mntopts_t *smo, mntopts_t *dmo)
{
	vfs_copyopttbl_extend(smo, dmo, 0);
}

static char **
vfs_mergecancelopts(const mntopt_t *mop1, const mntopt_t *mop2)
{
	int c1 = 0;
	int c2 = 0;
	char **result;
	char **sp1, **sp2, **dp;

	/*
	 * First we count both lists of cancel options.
	 * If either is NULL or has no elements, we return a copy of
	 * the other.
	 */
	if (mop1->mo_cancel != NULL) {
		for (; mop1->mo_cancel[c1] != NULL; c1++)
			/* count cancel options in mop1 */;
	}

	if (c1 == 0)
		return (vfs_copycancelopt_extend(mop2->mo_cancel, 0));

	if (mop2->mo_cancel != NULL) {
		for (; mop2->mo_cancel[c2] != NULL; c2++)
			/* count cancel options in mop2 */;
	}

	result = vfs_copycancelopt_extend(mop1->mo_cancel, c2);

	if (c2 == 0)
		return (result);

	/*
	 * When we get here, we've got two sets of cancel options;
	 * we need to merge the two sets.  We know that the result
	 * array has "c1+c2+1" entries and in the end we might shrink
	 * it.
	 * Result now has a copy of the c1 entries from mop1; we'll
	 * now lookup all the entries of mop2 in mop1 and copy it if
	 * it is unique.
	 * This operation is O(n^2) but it's only called once per
	 * filesystem per duplicate option.  This is a situation
	 * which doesn't arise with the filesystems in ON and
	 * n is generally 1.
	 */

	dp = &result[c1];
	for (sp2 = mop2->mo_cancel; *sp2 != NULL; sp2++) {
		for (sp1 = mop1->mo_cancel; *sp1 != NULL; sp1++) {
			if (strcmp(*sp1, *sp2) == 0)
				break;
		}
		if (*sp1 == NULL) {
			/*
			 * Option *sp2 not found in mop1, so copy it.
			 * The calls to vfs_copycancelopt_extend()
			 * guarantee that there's enough room.
			 */
			*dp = kmem_alloc(strlen(*sp2) + 1, KM_SLEEP);
			(void) strcpy(*dp++, *sp2);
		}
	}
	if (dp != &result[c1+c2]) {
		size_t bytes = (dp - result + 1) * sizeof (char *);
		char **nres = kmem_alloc(bytes, KM_SLEEP);

		bcopy(result, nres, bytes);
		kmem_free(result, (c1 + c2 + 1) * sizeof (char *));
		result = nres;
	}
	return (result);
}

/*
 * Merge two mount option tables (outer and inner) into one.  This is very
 * similar to "merging" global variables and automatic variables in C.
 *
 * This isn't (and doesn't have to be) fast.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect omo, imo & dmo.
 */
void
vfs_mergeopttbl(const mntopts_t *omo, const mntopts_t *imo, mntopts_t *dmo)
{
	uint_t i, count;
	mntopt_t *mop, *motbl;
	uint_t freeidx;

	/*
	 * First determine how much space we need to allocate.
	 */
	count = omo->mo_count;
	for (i = 0; i < imo->mo_count; i++) {
		if (imo->mo_list[i].mo_flags & MO_EMPTY)
			continue;
		if (vfs_hasopt(omo, imo->mo_list[i].mo_name) == NULL)
			count++;
	}
	ASSERT(count >= omo->mo_count &&
	    count <= omo->mo_count + imo->mo_count);
	motbl = kmem_alloc(count * sizeof (mntopt_t), KM_SLEEP);
	for (i = 0; i < omo->mo_count; i++)
		vfs_copyopt(&omo->mo_list[i], &motbl[i]);
	freeidx = omo->mo_count;
	for (i = 0; i < imo->mo_count; i++) {
		if (imo->mo_list[i].mo_flags & MO_EMPTY)
			continue;
		if ((mop = vfs_hasopt(omo, imo->mo_list[i].mo_name)) != NULL) {
			char **newcanp;
			uint_t index = mop - omo->mo_list;

			newcanp = vfs_mergecancelopts(mop, &motbl[index]);

			vfs_freeopt(&motbl[index]);
			vfs_copyopt(&imo->mo_list[i], &motbl[index]);

			vfs_freecancelopt(motbl[index].mo_cancel);
			motbl[index].mo_cancel = newcanp;
		} else {
			/*
			 * If it's a new option, just copy it over to the first
			 * free location.
			 */
			vfs_copyopt(&imo->mo_list[i], &motbl[freeidx++]);
		}
	}
	dmo->mo_count = count;
	dmo->mo_list = motbl;
}

/*
 * Functions to set and clear mount options in a mount options table.
 */

/*
 * Clear a mount option, if it exists.
 *
 * The update_mnttab arg indicates whether mops is part of a vfs that is on
 * the vfs list.
 */
static void
vfs_clearmntopt_nolock(mntopts_t *mops, const char *opt, int update_mnttab)
{
	struct mntopt *mop;
	uint_t i, count;

	ASSERT(!update_mnttab || RW_WRITE_HELD(&vfslist));

	count = mops->mo_count;
	for (i = 0; i < count; i++) {
		mop = &mops->mo_list[i];

		if (mop->mo_flags & MO_EMPTY)
			continue;
		if (strcmp(opt, mop->mo_name))
			continue;
		mop->mo_flags &= ~MO_SET;
		if (mop->mo_arg != NULL) {
			kmem_free(mop->mo_arg, strlen(mop->mo_arg) + 1);
		}
		mop->mo_arg = NULL;
		if (update_mnttab)
			vfs_mnttab_modtimeupd();
		break;
	}
}

void
vfs_clearmntopt(struct vfs *vfsp, const char *opt)
{
	int gotlock = 0;

	if (VFS_ON_LIST(vfsp)) {
		gotlock = 1;
		vfs_list_lock();
	}
	vfs_clearmntopt_nolock(&vfsp->vfs_mntopts, opt, gotlock);
	if (gotlock)
		vfs_list_unlock();
}


/*
 * Set a mount option on.  If it's not found in the table, it's silently
 * ignored.  If the option has MO_IGNORE set, it is still set unless the
 * VFS_NOFORCEOPT bit is set in the flags.  Also, VFS_DISPLAY/VFS_NODISPLAY flag
 * bits can be used to toggle the MO_NODISPLAY bit for the option.
 * If the VFS_CREATEOPT flag bit is set then the first option slot with
 * MO_EMPTY set is created as the option passed in.
 *
 * The update_mnttab arg indicates whether mops is part of a vfs that is on
 * the vfs list.
 */
static void
vfs_setmntopt_nolock(mntopts_t *mops, const char *opt,
    const char *arg, int flags, int update_mnttab)
{
	mntopt_t *mop;
	uint_t i, count;
	char *sp;

	ASSERT(!update_mnttab || RW_WRITE_HELD(&vfslist));

	if (flags & VFS_CREATEOPT) {
		if (vfs_hasopt(mops, opt) != NULL) {
			flags &= ~VFS_CREATEOPT;
		}
	}
	count = mops->mo_count;
	for (i = 0; i < count; i++) {
		mop = &mops->mo_list[i];

		if (mop->mo_flags & MO_EMPTY) {
			if ((flags & VFS_CREATEOPT) == 0)
				continue;
			sp = kmem_alloc(strlen(opt) + 1, KM_SLEEP);
			(void) strcpy(sp, opt);
			mop->mo_name = sp;
			if (arg != NULL)
				mop->mo_flags = MO_HASVALUE;
			else
				mop->mo_flags = 0;
		} else if (strcmp(opt, mop->mo_name)) {
			continue;
		}
		if ((mop->mo_flags & MO_IGNORE) && (flags & VFS_NOFORCEOPT))
			break;
		if (arg != NULL && (mop->mo_flags & MO_HASVALUE) != 0) {
			sp = kmem_alloc(strlen(arg) + 1, KM_SLEEP);
			(void) strcpy(sp, arg);
		} else {
			sp = NULL;
		}
		if (mop->mo_arg != NULL)
			kmem_free(mop->mo_arg, strlen(mop->mo_arg) + 1);
		mop->mo_arg = sp;
		if (flags & VFS_DISPLAY)
			mop->mo_flags &= ~MO_NODISPLAY;
		if (flags & VFS_NODISPLAY)
			mop->mo_flags |= MO_NODISPLAY;
		mop->mo_flags |= MO_SET;
		if (mop->mo_cancel != NULL) {
			char **cp;

			for (cp = mop->mo_cancel; *cp != NULL; cp++)
				vfs_clearmntopt_nolock(mops, *cp, 0);
		}
		if (update_mnttab)
			vfs_mnttab_modtimeupd();
		break;
	}
}

void
vfs_setmntopt(struct vfs *vfsp, const char *opt, const char *arg, int flags)
{
	int gotlock = 0;

	if (VFS_ON_LIST(vfsp)) {
		gotlock = 1;
		vfs_list_lock();
	}
	vfs_setmntopt_nolock(&vfsp->vfs_mntopts, opt, arg, flags, gotlock);
	if (gotlock)
		vfs_list_unlock();
}


/*
 * Add a "tag" option to a mounted file system's options list.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mops.
 */
static mntopt_t *
vfs_addtag(mntopts_t *mops, const char *tag)
{
	uint_t count;
	mntopt_t *mop, *motbl;

	count = mops->mo_count + 1;
	motbl = kmem_zalloc(count * sizeof (mntopt_t), KM_SLEEP);
	if (mops->mo_count) {
		size_t len = (count - 1) * sizeof (mntopt_t);

		bcopy(mops->mo_list, motbl, len);
		kmem_free(mops->mo_list, len);
	}
	mops->mo_count = count;
	mops->mo_list = motbl;
	mop = &motbl[count - 1];
	mop->mo_flags = MO_TAG;
	mop->mo_name = kmem_alloc(strlen(tag) + 1, KM_SLEEP);
	(void) strcpy(mop->mo_name, tag);
	return (mop);
}

/*
 * Allow users to set arbitrary "tags" in a vfs's mount options.
 * Broader use within the kernel is discouraged.
 */
int
vfs_settag(uint_t major, uint_t minor, const char *mntpt, const char *tag,
    cred_t *cr)
{
	vfs_t *vfsp;
	mntopts_t *mops;
	mntopt_t *mop;
	int found = 0;
	dev_t dev = makedevice(major, minor);
	int err = 0;
	char *buf = kmem_alloc(MAX_MNTOPT_STR, KM_SLEEP);

	/*
	 * Find the desired mounted file system
	 */
	vfs_list_lock();
	vfsp = rootvfs;
	do {
		if (vfsp->vfs_dev == dev &&
		    strcmp(mntpt, refstr_value(vfsp->vfs_mntpt)) == 0) {
			found = 1;
			break;
		}
		vfsp = vfsp->vfs_next;
	} while (vfsp != rootvfs);

	if (!found) {
		err = EINVAL;
		goto out;
	}
	err = secpolicy_fs_config(cr, vfsp);
	if (err != 0)
		goto out;

	mops = &vfsp->vfs_mntopts;
	/*
	 * Add tag if it doesn't already exist
	 */
	if ((mop = vfs_hasopt(mops, tag)) == NULL) {
		int len;

		(void) vfs_buildoptionstr(mops, buf, MAX_MNTOPT_STR);
		len = strlen(buf);
		if (len + strlen(tag) + 2 > MAX_MNTOPT_STR) {
			err = ENAMETOOLONG;
			goto out;
		}
		mop = vfs_addtag(mops, tag);
	}
	if ((mop->mo_flags & MO_TAG) == 0) {
		err = EINVAL;
		goto out;
	}
	vfs_setmntopt_nolock(mops, tag, NULL, 0, 1);
out:
	vfs_list_unlock();
	kmem_free(buf, MAX_MNTOPT_STR);
	return (err);
}

/*
 * Allow users to remove arbitrary "tags" in a vfs's mount options.
 * Broader use within the kernel is discouraged.
 */
int
vfs_clrtag(uint_t major, uint_t minor, const char *mntpt, const char *tag,
    cred_t *cr)
{
	vfs_t *vfsp;
	mntopt_t *mop;
	int found = 0;
	dev_t dev = makedevice(major, minor);
	int err = 0;

	/*
	 * Find the desired mounted file system
	 */
	vfs_list_lock();
	vfsp = rootvfs;
	do {
		if (vfsp->vfs_dev == dev &&
		    strcmp(mntpt, refstr_value(vfsp->vfs_mntpt)) == 0) {
			found = 1;
			break;
		}
		vfsp = vfsp->vfs_next;
	} while (vfsp != rootvfs);

	if (!found) {
		err = EINVAL;
		goto out;
	}
	err = secpolicy_fs_config(cr, vfsp);
	if (err != 0)
		goto out;

	if ((mop = vfs_hasopt(&vfsp->vfs_mntopts, tag)) == NULL) {
		err = EINVAL;
		goto out;
	}
	if ((mop->mo_flags & MO_TAG) == 0) {
		err = EINVAL;
		goto out;
	}
	vfs_clearmntopt_nolock(&vfsp->vfs_mntopts, tag, 1);
out:
	vfs_list_unlock();
	return (err);
}

/*
 * Function to parse an option string and fill in a mount options table.
 * Unknown options are silently ignored.  The input option string is modified
 * by replacing separators with nulls.  If the create flag is set, options
 * not found in the table are just added on the fly.  The table must have
 * an option slot marked MO_EMPTY to add an option on the fly.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mops..
 */
void
vfs_parsemntopts(mntopts_t *mops, char *osp, int create)
{
	char *s = osp, *p, *nextop, *valp, *cp, *ep;
	int setflg = VFS_NOFORCEOPT;

	if (osp == NULL)
		return;
	while (*s != '\0') {
		p = strchr(s, ',');	/* find next option */
		if (p == NULL) {
			cp = NULL;
			p = s + strlen(s);
		} else {
			cp = p;		/* save location of comma */
			*p++ = '\0';	/* mark end and point to next option */
		}
		nextop = p;
		p = strchr(s, '=');	/* look for value */
		if (p == NULL) {
			valp = NULL;	/* no value supplied */
		} else {
			ep = p;		/* save location of equals */
			*p++ = '\0';	/* end option and point to value */
			valp = p;
		}
		/*
		 * set option into options table
		 */
		if (create)
			setflg |= VFS_CREATEOPT;
		vfs_setmntopt_nolock(mops, s, valp, setflg, 0);
		if (cp != NULL)
			*cp = ',';	/* restore the comma */
		if (valp != NULL)
			*ep = '=';	/* restore the equals */
		s = nextop;
	}
}

/*
 * Function to inquire if an option exists in a mount options table.
 * Returns a pointer to the option if it exists, else NULL.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mops.
 */
struct mntopt *
vfs_hasopt(const mntopts_t *mops, const char *opt)
{
	struct mntopt *mop;
	uint_t i, count;

	count = mops->mo_count;
	for (i = 0; i < count; i++) {
		mop = &mops->mo_list[i];

		if (mop->mo_flags & MO_EMPTY)
			continue;
		if (strcmp(opt, mop->mo_name) == 0)
			return (mop);
	}
	return (NULL);
}

/*
 * Function to inquire if an option is set in a mount options table.
 * Returns non-zero if set and fills in the arg pointer with a pointer to
 * the argument string or NULL if there is no argument string.
 */
static int
vfs_optionisset_nolock(const mntopts_t *mops, const char *opt, char **argp)
{
	struct mntopt *mop;
	uint_t i, count;

	count = mops->mo_count;
	for (i = 0; i < count; i++) {
		mop = &mops->mo_list[i];

		if (mop->mo_flags & MO_EMPTY)
			continue;
		if (strcmp(opt, mop->mo_name))
			continue;
		if ((mop->mo_flags & MO_SET) == 0)
			return (0);
		if (argp != NULL && (mop->mo_flags & MO_HASVALUE) != 0)
			*argp = mop->mo_arg;
		return (1);
	}
	return (0);
}


int
vfs_optionisset(const struct vfs *vfsp, const char *opt, char **argp)
{
	int ret;

	vfs_list_read_lock();
	ret = vfs_optionisset_nolock(&vfsp->vfs_mntopts, opt, argp);
	vfs_list_unlock();
	return (ret);
}


/*
 * Construct a comma separated string of the options set in the given
 * mount table, return the string in the given buffer.  Return non-zero if
 * the buffer would overflow.
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mp.
 */
int
vfs_buildoptionstr(const mntopts_t *mp, char *buf, int len)
{
	char *cp;
	uint_t i;

	buf[0] = '\0';
	cp = buf;
	for (i = 0; i < mp->mo_count; i++) {
		struct mntopt *mop;

		mop = &mp->mo_list[i];
		if (mop->mo_flags & MO_SET) {
			int optlen, comma = 0;

			if (buf[0] != '\0')
				comma = 1;
			optlen = strlen(mop->mo_name);
			if (strlen(buf) + comma + optlen + 1 > len)
				goto err;
			if (comma)
				*cp++ = ',';
			(void) strcpy(cp, mop->mo_name);
			cp += optlen;
			/*
			 * Append option value if there is one
			 */
			if (mop->mo_arg != NULL) {
				int arglen;

				arglen = strlen(mop->mo_arg);
				if (strlen(buf) + arglen + 2 > len)
					goto err;
				*cp++ = '=';
				(void) strcpy(cp, mop->mo_arg);
				cp += arglen;
			}
		}
	}
	return (0);
err:
	return (EOVERFLOW);
}

static void
vfs_freecancelopt(char **moc)
{
	if (moc != NULL) {
		int ccnt = 0;
		char **cp;

		for (cp = moc; *cp != NULL; cp++) {
			kmem_free(*cp, strlen(*cp) + 1);
			ccnt++;
		}
		kmem_free(moc, (ccnt + 1) * sizeof (char *));
	}
}

static void
vfs_freeopt(mntopt_t *mop)
{
	if (mop->mo_name != NULL)
		kmem_free(mop->mo_name, strlen(mop->mo_name) + 1);

	vfs_freecancelopt(mop->mo_cancel);

	if (mop->mo_arg != NULL)
		kmem_free(mop->mo_arg, strlen(mop->mo_arg) + 1);
}

/*
 * Free a mount options table
 *
 * This function is *not* for general use by filesystems.
 *
 * Note: caller is responsible for locking the vfs list, if needed,
 *       to protect mp.
 */
void
vfs_freeopttbl(mntopts_t *mp)
{
	uint_t i, count;

	count = mp->mo_count;
	for (i = 0; i < count; i++) {
		vfs_freeopt(&mp->mo_list[i]);
	}
	if (count) {
		kmem_free(mp->mo_list, sizeof (mntopt_t) * count);
		mp->mo_count = 0;
		mp->mo_list = NULL;
	}
}


/* ARGSUSED */
static int
vfs_mntdummyread(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cred,
	caller_context_t *ct)
{
	return (0);
}

/* ARGSUSED */
static int
vfs_mntdummywrite(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cred,
	caller_context_t *ct)
{
	return (0);
}

/*
 * The dummy vnode is currently used only by file events notification
 * module which is just interested in the timestamps.
 */
/* ARGSUSED */
static int
vfs_mntdummygetattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
    caller_context_t *ct)
{
	bzero(vap, sizeof (vattr_t));
	vap->va_type = VREG;
	vap->va_nlink = 1;
	vap->va_ctime = vfs_mnttab_ctime;
	/*
	 * it is ok to just copy mtime as the time will be monotonically
	 * increasing.
	 */
	vap->va_mtime = vfs_mnttab_mtime;
	vap->va_atime = vap->va_mtime;
	return (0);
}

static void
vfs_mnttabvp_setup(void)
{
	vnode_t *tvp;
	vnodeops_t *vfs_mntdummyvnops;
	const fs_operation_def_t mnt_dummyvnodeops_template[] = {
		VOPNAME_READ, 		{ .vop_read = vfs_mntdummyread },
		VOPNAME_WRITE, 		{ .vop_write = vfs_mntdummywrite },
		VOPNAME_GETATTR,	{ .vop_getattr = vfs_mntdummygetattr },
		VOPNAME_VNEVENT,	{ .vop_vnevent = fs_vnevent_support },
		NULL,			NULL
	};

	if (vn_make_ops("mnttab", mnt_dummyvnodeops_template,
	    &vfs_mntdummyvnops) != 0) {
		cmn_err(CE_WARN, "vfs_mnttabvp_setup: vn_make_ops failed");
		/* Shouldn't happen, but not bad enough to panic */
		return;
	}

	/*
	 * A global dummy vnode is allocated to represent mntfs files.
	 * The mntfs file (/etc/mnttab) can be monitored for file events
	 * and receive an event when mnttab changes. Dummy VOP calls
	 * will be made on this vnode. The file events notification module
	 * intercepts this vnode and delivers relevant events.
	 */
	tvp = vn_alloc(KM_SLEEP);
	tvp->v_flag = VNOMOUNT|VNOMAP|VNOSWAP|VNOCACHE;
	vn_setops(tvp, vfs_mntdummyvnops);
	tvp->v_type = VREG;
	/*
	 * The mnt dummy ops do not reference v_data.
	 * No other module intercepting this vnode should either.
	 * Just set it to point to itself.
	 */
	tvp->v_data = (caddr_t)tvp;
	tvp->v_vfsp = rootvfs;
	vfs_mntdummyvp = tvp;
}

/*
 * performs fake read/write ops
 */
static void
vfs_mnttab_rwop(int rw)
{
	struct uio	uio;
	struct iovec	iov;
	char	buf[1];

	if (vfs_mntdummyvp == NULL)
		return;

	bzero(&uio, sizeof (uio));
	bzero(&iov, sizeof (iov));
	iov.iov_base = buf;
	iov.iov_len = 0;
	uio.uio_iov = &iov;
	uio.uio_iovcnt = 1;
	uio.uio_loffset = 0;
	uio.uio_segflg = UIO_SYSSPACE;
	uio.uio_resid = 0;
	if (rw) {
		(void) VOP_WRITE(vfs_mntdummyvp, &uio, 0, kcred, NULL);
	} else {
		(void) VOP_READ(vfs_mntdummyvp, &uio, 0, kcred, NULL);
	}
}

/*
 * Generate a write operation.
 */
void
vfs_mnttab_writeop(void)
{
	vfs_mnttab_rwop(1);
}

/*
 * Generate a read operation.
 */
void
vfs_mnttab_readop(void)
{
	vfs_mnttab_rwop(0);
}

/*
 * Free any mnttab information recorded in the vfs struct.
 * The vfs must not be on the vfs list.
 */
static void
vfs_freemnttab(struct vfs *vfsp)
{
	ASSERT(!VFS_ON_LIST(vfsp));

	/*
	 * Free device and mount point information
	 */
	if (vfsp->vfs_mntpt != NULL) {
		refstr_rele(vfsp->vfs_mntpt);
		vfsp->vfs_mntpt = NULL;
	}
	if (vfsp->vfs_resource != NULL) {
		refstr_rele(vfsp->vfs_resource);
		vfsp->vfs_resource = NULL;
	}
	/*
	 * Now free mount options information
	 */
	vfs_freeopttbl(&vfsp->vfs_mntopts);
}

/*
 * Return the last mnttab modification time
 */
void
vfs_mnttab_modtime(timespec_t *ts)
{
	ASSERT(RW_LOCK_HELD(&vfslist));
	*ts = vfs_mnttab_mtime;
}

/*
 * See if mnttab is changed
 */
void
vfs_mnttab_poll(timespec_t *old, struct pollhead **phpp)
{
	int changed;

	*phpp = (struct pollhead *)NULL;

	/*
	 * Note: don't grab vfs list lock before accessing vfs_mnttab_mtime.
	 * Can lead to deadlock against vfs_mnttab_modtimeupd(). It is safe
	 * to not grab the vfs list lock because tv_sec is monotonically
	 * increasing.
	 */

	changed = (old->tv_nsec != vfs_mnttab_mtime.tv_nsec) ||
	    (old->tv_sec != vfs_mnttab_mtime.tv_sec);
	if (!changed) {
		*phpp = &vfs_pollhd;
	}
}

/* Provide a unique and monotonically-increasing timestamp. */
void
vfs_mono_time(timespec_t *ts)
{
	static volatile hrtime_t hrt;		/* The saved time. */
	hrtime_t	newhrt, oldhrt;		/* For effecting the CAS. */
	timespec_t	newts;

	/*
	 * Try gethrestime() first, but be prepared to fabricate a sensible
	 * answer at the first sign of any trouble.
	 */
	gethrestime(&newts);
	newhrt = ts2hrt(&newts);
	for (;;) {
		oldhrt = hrt;
		if (newhrt <= hrt)
			newhrt = hrt + 1;
		if (atomic_cas_64((uint64_t *)&hrt, oldhrt, newhrt) == oldhrt)
			break;
	}
	hrt2ts(newhrt, ts);
}

/*
 * Update the mnttab modification time and wake up any waiters for
 * mnttab changes
 */
void
vfs_mnttab_modtimeupd()
{
	hrtime_t oldhrt, newhrt;

	ASSERT(RW_WRITE_HELD(&vfslist));
	oldhrt = ts2hrt(&vfs_mnttab_mtime);
	gethrestime(&vfs_mnttab_mtime);
	newhrt = ts2hrt(&vfs_mnttab_mtime);
	if (oldhrt == (hrtime_t)0)
		vfs_mnttab_ctime = vfs_mnttab_mtime;
	/*
	 * Attempt to provide unique mtime (like uniqtime but not).
	 */
	if (newhrt == oldhrt) {
		newhrt++;
		hrt2ts(newhrt, &vfs_mnttab_mtime);
	}
	pollwakeup(&vfs_pollhd, (short)POLLRDBAND);
	vfs_mnttab_writeop();
}

int
dounmount(struct vfs *vfsp, int flag, cred_t *cr)
{
	vnode_t *coveredvp;
	int error;
	extern void teardown_vopstats(vfs_t *);

	/*
	 * Get covered vnode. This will be NULL if the vfs is not linked
	 * into the file system name space (i.e., domount() with MNT_NOSPICE).
	 */
	coveredvp = vfsp->vfs_vnodecovered;
	ASSERT(coveredvp == NULL || vn_vfswlock_held(coveredvp));

	/*
	 * Purge all dnlc entries for this vfs.
	 */
	(void) dnlc_purge_vfsp(vfsp, 0);

	/* For forcible umount, skip VFS_SYNC() since it may hang */
	if ((flag & MS_FORCE) == 0)
		(void) VFS_SYNC(vfsp, 0, cr);

	/*
	 * Lock the vfs to maintain fs status quo during unmount.  This
	 * has to be done after the sync because ufs_update tries to acquire
	 * the vfs_reflock.
	 */
	vfs_lock_wait(vfsp);

	if (error = VFS_UNMOUNT(vfsp, flag, cr)) {
		vfs_unlock(vfsp);
		if (coveredvp != NULL)
			vn_vfsunlock(coveredvp);
	} else if (coveredvp != NULL) {
		teardown_vopstats(vfsp);
		/*
		 * vfs_remove() will do a VN_RELE(vfsp->vfs_vnodecovered)
		 * when it frees vfsp so we do a VN_HOLD() so we can
		 * continue to use coveredvp afterwards.
		 */
		VN_HOLD(coveredvp);
		vfs_remove(vfsp);
		vn_vfsunlock(coveredvp);
		VN_RELE(coveredvp);
	} else {
		teardown_vopstats(vfsp);
		/*
		 * Release the reference to vfs that is not linked
		 * into the name space.
		 */
		vfs_unlock(vfsp);
		VFS_RELE(vfsp);
	}
	return (error);
}


/*
 * Vfs_unmountall() is called by uadmin() to unmount all
 * mounted file systems (except the root file system) during shutdown.
 * It follows the existing locking protocol when traversing the vfs list
 * to sync and unmount vfses. Even though there should be no
 * other thread running while the system is shutting down, it is prudent
 * to still follow the locking protocol.
 */
void
vfs_unmountall(void)
{
	struct vfs *vfsp;
	struct vfs *prev_vfsp = NULL;
	int error;

	/*
	 * Toss all dnlc entries now so that the per-vfs sync
	 * and unmount operations don't have to slog through
	 * a bunch of uninteresting vnodes over and over again.
	 */
	dnlc_purge();

	vfs_list_lock();
	for (vfsp = rootvfs->vfs_prev; vfsp != rootvfs; vfsp = prev_vfsp) {
		prev_vfsp = vfsp->vfs_prev;

		if (vfs_lock(vfsp) != 0)
			continue;
		error = vn_vfswlock(vfsp->vfs_vnodecovered);
		vfs_unlock(vfsp);
		if (error)
			continue;

		vfs_list_unlock();

		(void) VFS_SYNC(vfsp, SYNC_CLOSE, CRED());
		(void) dounmount(vfsp, 0, CRED());

		/*
		 * Since we dropped the vfslist lock above we must
		 * verify that next_vfsp still exists, else start over.
		 */
		vfs_list_lock();
		for (vfsp = rootvfs->vfs_prev;
		    vfsp != rootvfs; vfsp = vfsp->vfs_prev)
			if (vfsp == prev_vfsp)
				break;
		if (vfsp == rootvfs && prev_vfsp != rootvfs)
			prev_vfsp = rootvfs->vfs_prev;
	}
	vfs_list_unlock();
}

/*
 * Called to add an entry to the end of the vfs mount in progress list
 */
void
vfs_addmip(dev_t dev, struct vfs *vfsp)
{
	struct ipmnt *mipp;

	mipp = (struct ipmnt *)kmem_alloc(sizeof (struct ipmnt), KM_SLEEP);
	mipp->mip_next = NULL;
	mipp->mip_dev = dev;
	mipp->mip_vfsp = vfsp;
	mutex_enter(&vfs_miplist_mutex);
	if (vfs_miplist_end != NULL)
		vfs_miplist_end->mip_next = mipp;
	else
		vfs_miplist = mipp;
	vfs_miplist_end = mipp;
	mutex_exit(&vfs_miplist_mutex);
}

/*
 * Called to remove an entry from the mount in progress list
 * Either because the mount completed or it failed.
 */
void
vfs_delmip(struct vfs *vfsp)
{
	struct ipmnt *mipp, *mipprev;

	mutex_enter(&vfs_miplist_mutex);
	mipprev = NULL;
	for (mipp = vfs_miplist;
	    mipp && mipp->mip_vfsp != vfsp; mipp = mipp->mip_next) {
		mipprev = mipp;
	}
	if (mipp == NULL)
		return; /* shouldn't happen */
	if (mipp == vfs_miplist_end)
		vfs_miplist_end = mipprev;
	if (mipprev == NULL)
		vfs_miplist = mipp->mip_next;
	else
		mipprev->mip_next = mipp->mip_next;
	mutex_exit(&vfs_miplist_mutex);
	kmem_free(mipp, sizeof (struct ipmnt));
}

/*
 * vfs_add is called by a specific filesystem's mount routine to add
 * the new vfs into the vfs list/hash and to cover the mounted-on vnode.
 * The vfs should already have been locked by the caller.
 *
 * coveredvp is NULL if this is the root.
 */
void
vfs_add(vnode_t *coveredvp, struct vfs *vfsp, int mflag)
{
	int newflag;

	ASSERT(vfs_lock_held(vfsp));
	VFS_HOLD(vfsp);
	newflag = vfsp->vfs_flag;
	if (mflag & MS_RDONLY)
		newflag |= VFS_RDONLY;
	else
		newflag &= ~VFS_RDONLY;
	if (mflag & MS_NOSUID)
		newflag |= (VFS_NOSETUID|VFS_NODEVICES);
	else
		newflag &= ~(VFS_NOSETUID|VFS_NODEVICES);
	if (mflag & MS_NOMNTTAB)
		newflag |= VFS_NOMNTTAB;
	else
		newflag &= ~VFS_NOMNTTAB;

	if (coveredvp != NULL) {
		ASSERT(vn_vfswlock_held(coveredvp));
		coveredvp->v_vfsmountedhere = vfsp;
		VN_HOLD(coveredvp);
	}
	vfsp->vfs_vnodecovered = coveredvp;
	vfsp->vfs_flag = newflag;

	vfs_list_add(vfsp);
}

/*
 * Remove a vfs from the vfs list, null out the pointer from the
 * covered vnode to the vfs (v_vfsmountedhere), and null out the pointer
 * from the vfs to the covered vnode (vfs_vnodecovered). Release the
 * reference to the vfs and to the covered vnode.
 *
 * Called from dounmount after it's confirmed with the file system
 * that the unmount is legal.
 */
void
vfs_remove(struct vfs *vfsp)
{
	vnode_t *vp;

	ASSERT(vfs_lock_held(vfsp));

	/*
	 * Can't unmount root.  Should never happen because fs will
	 * be busy.
	 */
	if (vfsp == rootvfs)
		panic("vfs_remove: unmounting root");

	vfs_list_remove(vfsp);

	/*
	 * Unhook from the file system name space.
	 */
	vp = vfsp->vfs_vnodecovered;
	ASSERT(vn_vfswlock_held(vp));
	vp->v_vfsmountedhere = NULL;
	vfsp->vfs_vnodecovered = NULL;
	VN_RELE(vp);

	/*
	 * Release lock and wakeup anybody waiting.
	 */
	vfs_unlock(vfsp);
	VFS_RELE(vfsp);
}

/*
 * Lock a filesystem to prevent access to it while mounting,
 * unmounting and syncing.  Return EBUSY immediately if lock
 * can't be acquired.
 */
int
vfs_lock(vfs_t *vfsp)
{
	vn_vfslocks_entry_t *vpvfsentry;

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	if (rwst_tryenter(&vpvfsentry->ve_lock, RW_WRITER))
		return (0);

	vn_vfslocks_rele(vpvfsentry);
	return (EBUSY);
}

int
vfs_rlock(vfs_t *vfsp)
{
	vn_vfslocks_entry_t *vpvfsentry;

	vpvfsentry = vn_vfslocks_getlock(vfsp);

	if (rwst_tryenter(&vpvfsentry->ve_lock, RW_READER))
		return (0);

	vn_vfslocks_rele(vpvfsentry);
	return (EBUSY);
}

void
vfs_lock_wait(vfs_t *vfsp)
{
	vn_vfslocks_entry_t *vpvfsentry;

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	rwst_enter(&vpvfsentry->ve_lock, RW_WRITER);
}

void
vfs_rlock_wait(vfs_t *vfsp)
{
	vn_vfslocks_entry_t *vpvfsentry;

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	rwst_enter(&vpvfsentry->ve_lock, RW_READER);
}

/*
 * Unlock a locked filesystem.
 */
void
vfs_unlock(vfs_t *vfsp)
{
	vn_vfslocks_entry_t *vpvfsentry;

	/*
	 * vfs_unlock will mimic sema_v behaviour to fix 4748018.
	 * And these changes should remain for the patch changes as it is.
	 */
	if (panicstr)
		return;

	/*
	 * ve_refcount needs to be dropped twice here.
	 * 1. To release refernce after a call to vfs_locks_getlock()
	 * 2. To release the reference from the locking routines like
	 *    vfs_rlock_wait/vfs_wlock_wait/vfs_wlock etc,.
	 */

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	vn_vfslocks_rele(vpvfsentry);

	rwst_exit(&vpvfsentry->ve_lock);
	vn_vfslocks_rele(vpvfsentry);
}

/*
 * Utility routine that allows a filesystem to construct its
 * fsid in "the usual way" - by munging some underlying dev_t and
 * the filesystem type number into the 64-bit fsid.  Note that
 * this implicitly relies on dev_t persistence to make filesystem
 * id's persistent.
 *
 * There's nothing to prevent an individual fs from constructing its
 * fsid in a different way, and indeed they should.
 *
 * Since we want fsids to be 32-bit quantities (so that they can be
 * exported identically by either 32-bit or 64-bit APIs, as well as
 * the fact that fsid's are "known" to NFS), we compress the device
 * number given down to 32-bits, and panic if that isn't possible.
 */
void
vfs_make_fsid(fsid_t *fsi, dev_t dev, int val)
{
	if (!cmpldev((dev32_t *)&fsi->val[0], dev))
		panic("device number too big for fsid!");
	fsi->val[1] = val;
}

int
vfs_lock_held(vfs_t *vfsp)
{
	int held;
	vn_vfslocks_entry_t *vpvfsentry;

	/*
	 * vfs_lock_held will mimic sema_held behaviour
	 * if panicstr is set. And these changes should remain
	 * for the patch changes as it is.
	 */
	if (panicstr)
		return (1);

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	held = rwst_lock_held(&vpvfsentry->ve_lock, RW_WRITER);

	vn_vfslocks_rele(vpvfsentry);
	return (held);
}

struct _kthread *
vfs_lock_owner(vfs_t *vfsp)
{
	struct _kthread *owner;
	vn_vfslocks_entry_t *vpvfsentry;

	/*
	 * vfs_wlock_held will mimic sema_held behaviour
	 * if panicstr is set. And these changes should remain
	 * for the patch changes as it is.
	 */
	if (panicstr)
		return (NULL);

	vpvfsentry = vn_vfslocks_getlock(vfsp);
	owner = rwst_owner(&vpvfsentry->ve_lock);

	vn_vfslocks_rele(vpvfsentry);
	return (owner);
}

/*
 * vfs list locking.
 *
 * Rather than manipulate the vfslist lock directly, we abstract into lock
 * and unlock routines to allow the locking implementation to be changed for
 * clustering.
 *
 * Whenever the vfs list is modified through its hash links, the overall list
 * lock must be obtained before locking the relevant hash bucket.  But to see
 * whether a given vfs is on the list, it suffices to obtain the lock for the
 * hash bucket without getting the overall list lock.  (See getvfs() below.)
 */

void
vfs_list_lock()
{
	rw_enter(&vfslist, RW_WRITER);
}

void
vfs_list_read_lock()
{
	rw_enter(&vfslist, RW_READER);
}

void
vfs_list_unlock()
{
	rw_exit(&vfslist);
}

/*
 * Low level worker routines for adding entries to and removing entries from
 * the vfs list.
 */

static void
vfs_hash_add(struct vfs *vfsp, int insert_at_head)
{
	int vhno;
	struct vfs **hp;
	dev_t dev;

	ASSERT(RW_WRITE_HELD(&vfslist));

	dev = expldev(vfsp->vfs_fsid.val[0]);
	vhno = VFSHASH(getmajor(dev), getminor(dev));

	mutex_enter(&rvfs_list[vhno].rvfs_lock);

	/*
	 * Link into the hash table, inserting it at the end, so that LOFS
	 * with the same fsid as UFS (or other) file systems will not hide the
	 * UFS.
	 */
	if (insert_at_head) {
		vfsp->vfs_hash = rvfs_list[vhno].rvfs_head;
		rvfs_list[vhno].rvfs_head = vfsp;
	} else {
		for (hp = &rvfs_list[vhno].rvfs_head; *hp != NULL;
		    hp = &(*hp)->vfs_hash)
			continue;
		/*
		 * hp now contains the address of the pointer to update
		 * to effect the insertion.
		 */
		vfsp->vfs_hash = NULL;
		*hp = vfsp;
	}

	rvfs_list[vhno].rvfs_len++;
	mutex_exit(&rvfs_list[vhno].rvfs_lock);
}


static void
vfs_hash_remove(struct vfs *vfsp)
{
	int vhno;
	struct vfs *tvfsp;
	dev_t dev;

	ASSERT(RW_WRITE_HELD(&vfslist));

	dev = expldev(vfsp->vfs_fsid.val[0]);
	vhno = VFSHASH(getmajor(dev), getminor(dev));

	mutex_enter(&rvfs_list[vhno].rvfs_lock);

	/*
	 * Remove from hash.
	 */
	if (rvfs_list[vhno].rvfs_head == vfsp) {
		rvfs_list[vhno].rvfs_head = vfsp->vfs_hash;
		rvfs_list[vhno].rvfs_len--;
		goto foundit;
	}
	for (tvfsp = rvfs_list[vhno].rvfs_head; tvfsp != NULL;
	    tvfsp = tvfsp->vfs_hash) {
		if (tvfsp->vfs_hash == vfsp) {
			tvfsp->vfs_hash = vfsp->vfs_hash;
			rvfs_list[vhno].rvfs_len--;
			goto foundit;
		}
	}
	cmn_err(CE_WARN, "vfs_list_remove: vfs not found in hash");

foundit:

	mutex_exit(&rvfs_list[vhno].rvfs_lock);
}


void
vfs_list_add(struct vfs *vfsp)
{
	zone_t *zone;

	/*
	 * Typically, the vfs_t will have been created on behalf of the file
	 * system in vfs_init, where it will have been provided with a
	 * vfs_impl_t. This, however, might be lacking if the vfs_t was created
	 * by an unbundled file system. We therefore check for such an example
	 * before stamping the vfs_t with its creation time for the benefit of
	 * mntfs.
	 */
	if (vfsp->vfs_implp == NULL)
		vfsimpl_setup(vfsp);
	vfs_mono_time(&vfsp->vfs_hrctime);

	/*
	 * The zone that owns the mount is the one that performed the mount.
	 * Note that this isn't necessarily the same as the zone mounted into.
	 * The corresponding zone_rele_ref() will be done when the vfs_t
	 * is being free'd.
	 */
	vfsp->vfs_zone = curproc->p_zone;
	zone_init_ref(&vfsp->vfs_implp->vi_zone_ref);
	zone_hold_ref(vfsp->vfs_zone, &vfsp->vfs_implp->vi_zone_ref,
	    ZONE_REF_VFS);

	/*
	 * Find the zone mounted into, and put this mount on its vfs list.
	 */
	zone = zone_find_by_path(refstr_value(vfsp->vfs_mntpt));
	ASSERT(zone != NULL);
	/*
	 * Special casing for the root vfs.  This structure is allocated
	 * statically and hooked onto rootvfs at link time.  During the
	 * vfs_mountroot call at system startup time, the root file system's
	 * VFS_MOUNTROOT routine will call vfs_add with this root vfs struct
	 * as argument.  The code below must detect and handle this special
	 * case.  The only apparent justification for this special casing is
	 * to ensure that the root file system appears at the head of the
	 * list.
	 *
	 * XXX:	I'm assuming that it's ok to do normal list locking when
	 *	adding the entry for the root file system (this used to be
	 *	done with no locks held).
	 */
	vfs_list_lock();
	/*
	 * Link into the vfs list proper.
	 */
	if (vfsp == &root) {
		/*
		 * Assert: This vfs is already on the list as its first entry.
		 * Thus, there's nothing to do.
		 */
		ASSERT(rootvfs == vfsp);
		/*
		 * Add it to the head of the global zone's vfslist.
		 */
		ASSERT(zone == global_zone);
		ASSERT(zone->zone_vfslist == NULL);
		zone->zone_vfslist = vfsp;
	} else {
		/*
		 * Link to end of list using vfs_prev (as rootvfs is now a
		 * doubly linked circular list) so list is in mount order for
		 * mnttab use.
		 */
		rootvfs->vfs_prev->vfs_next = vfsp;
		vfsp->vfs_prev = rootvfs->vfs_prev;
		rootvfs->vfs_prev = vfsp;
		vfsp->vfs_next = rootvfs;

		/*
		 * Do it again for the zone-private list (which may be NULL).
		 */
		if (zone->zone_vfslist == NULL) {
			ASSERT(zone != global_zone);
			zone->zone_vfslist = vfsp;
		} else {
			zone->zone_vfslist->vfs_zone_prev->vfs_zone_next = vfsp;
			vfsp->vfs_zone_prev = zone->zone_vfslist->vfs_zone_prev;
			zone->zone_vfslist->vfs_zone_prev = vfsp;
			vfsp->vfs_zone_next = zone->zone_vfslist;
		}
	}

	/*
	 * Link into the hash table, inserting it at the end, so that LOFS
	 * with the same fsid as UFS (or other) file systems will not hide
	 * the UFS.
	 */
	vfs_hash_add(vfsp, 0);

	/*
	 * Link into tree indexed by mntpoint, for vfs_mntpoint2vfsp
	 * mntix discerns entries with the same key
	 */
	vfsp->vfs_mntix = ++vfs_curr_mntix;
	avl_add(&vfs_by_dev, vfsp);

	/*
	 * Link into tree indexed by dev, for vfs_devismounted
	 */
	avl_add(&vfs_by_mntpnt, vfsp);

	/*
	 * update the mnttab modification time
	 */
	vfs_mnttab_modtimeupd();
	vfs_list_unlock();
	zone_rele(zone);
}

void
vfs_list_remove(struct vfs *vfsp)
{
	zone_t *zone;

	zone = zone_find_by_path(refstr_value(vfsp->vfs_mntpt));
	ASSERT(zone != NULL);
	/*
	 * Callers are responsible for preventing attempts to unmount the
	 * root.
	 */
	ASSERT(vfsp != rootvfs);

	vfs_list_lock();

	/*
	 * Remove from avl trees
	 */
	avl_remove(&vfs_by_mntpnt, vfsp);
	avl_remove(&vfs_by_dev, vfsp);

	/*
	 * Remove from hash.
	 */
	vfs_hash_remove(vfsp);

	/*
	 * Remove from vfs list.
	 */
	vfsp->vfs_prev->vfs_next = vfsp->vfs_next;
	vfsp->vfs_next->vfs_prev = vfsp->vfs_prev;
	vfsp->vfs_next = vfsp->vfs_prev = NULL;

	/*
	 * Remove from zone-specific vfs list.
	 */
	if (zone->zone_vfslist == vfsp)
		zone->zone_vfslist = vfsp->vfs_zone_next;

	if (vfsp->vfs_zone_next == vfsp) {
		ASSERT(vfsp->vfs_zone_prev == vfsp);
		ASSERT(zone->zone_vfslist == vfsp);
		zone->zone_vfslist = NULL;
	}

	vfsp->vfs_zone_prev->vfs_zone_next = vfsp->vfs_zone_next;
	vfsp->vfs_zone_next->vfs_zone_prev = vfsp->vfs_zone_prev;
	vfsp->vfs_zone_next = vfsp->vfs_zone_prev = NULL;

	/*
	 * update the mnttab modification time
	 */
	vfs_mnttab_modtimeupd();
	vfs_list_unlock();
	zone_rele(zone);
}

struct vfs *
getvfs(fsid_t *fsid)
{
	struct vfs *vfsp;
	int val0 = fsid->val[0];
	int val1 = fsid->val[1];
	dev_t dev = expldev(val0);
	int vhno = VFSHASH(getmajor(dev), getminor(dev));
	kmutex_t *hmp = &rvfs_list[vhno].rvfs_lock;

	mutex_enter(hmp);
	for (vfsp = rvfs_list[vhno].rvfs_head; vfsp; vfsp = vfsp->vfs_hash) {
		if (vfsp->vfs_fsid.val[0] == val0 &&
		    vfsp->vfs_fsid.val[1] == val1) {
			VFS_HOLD(vfsp);
			mutex_exit(hmp);
			return (vfsp);
		}
	}
	mutex_exit(hmp);
	return (NULL);
}

/*
 * Search the vfs mount in progress list for a specified device/vfs entry.
 * Returns 0 if the first entry in the list that the device matches has the
 * given vfs pointer as well.  If the device matches but a different vfs
 * pointer is encountered in the list before the given vfs pointer then
 * a 1 is returned.
 */

int
vfs_devmounting(dev_t dev, struct vfs *vfsp)
{
	int retval = 0;
	struct ipmnt *mipp;

	mutex_enter(&vfs_miplist_mutex);
	for (mipp = vfs_miplist; mipp != NULL; mipp = mipp->mip_next) {
		if (mipp->mip_dev == dev) {
			if (mipp->mip_vfsp != vfsp)
				retval = 1;
			break;
		}
	}
	mutex_exit(&vfs_miplist_mutex);
	return (retval);
}

/*
 * Search the vfs list for a specified device.  Returns 1, if entry is found
 * or 0 if no suitable entry is found.
 */

int
vfs_devismounted(dev_t dev)
{
	struct vfs *vfsp;
	int found = 0;
	struct vfs search;
	avl_index_t index;

	search.vfs_dev = dev;
	search.vfs_mntix = 0;

	vfs_list_read_lock();

	/*
	 * there might be several entries with the same dev in the tree,
	 * only discerned by mntix. To find the first, we start with a mntix
	 * of 0. The search will fail. The following avl_nearest will give
	 * us the actual first entry.
	 */
	VERIFY(avl_find(&vfs_by_dev, &search, &index) == NULL);
	vfsp = avl_nearest(&vfs_by_dev, index, AVL_AFTER);

	if (vfsp != NULL && vfsp->vfs_dev == dev)
		found = 1;

	vfs_list_unlock();
	return (found);
}

/*
 * Search the vfs list for a specified device.  Returns a pointer to it
 * or NULL if no suitable entry is found. The caller of this routine
 * is responsible for releasing the returned vfs pointer.
 */
struct vfs *
vfs_dev2vfsp(dev_t dev)
{
	struct vfs *vfsp;
	int found;
	struct vfs search;
	avl_index_t index;

	search.vfs_dev = dev;
	search.vfs_mntix = 0;

	vfs_list_read_lock();

	/*
	 * there might be several entries with the same dev in the tree,
	 * only discerned by mntix. To find the first, we start with a mntix
	 * of 0. The search will fail. The following avl_nearest will give
	 * us the actual first entry.
	 */
	VERIFY(avl_find(&vfs_by_dev, &search, &index) == NULL);
	vfsp = avl_nearest(&vfs_by_dev, index, AVL_AFTER);

	found = 0;
	while (vfsp != NULL && vfsp->vfs_dev == dev) {
		/*
		 * The following could be made more efficient by making
		 * the entire loop use vfs_zone_next if the call is from
		 * a zone.  The only callers, however, ustat(2) and
		 * umount2(2), don't seem to justify the added
		 * complexity at present.
		 */
		if (ZONE_PATH_VISIBLE(refstr_value(vfsp->vfs_mntpt),
		    curproc->p_zone)) {
			VFS_HOLD(vfsp);
			found = 1;
			break;
		}
		vfsp = AVL_NEXT(&vfs_by_dev, vfsp);
	}
	vfs_list_unlock();
	return (found ? vfsp : NULL);
}

/*
 * Search the vfs list for a specified mntpoint.  Returns a pointer to it
 * or NULL if no suitable entry is found. The caller of this routine
 * is responsible for releasing the returned vfs pointer.
 *
 * Note that if multiple mntpoints match, the last one matching is
 * returned in an attempt to return the "top" mount when overlay
 * mounts are covering the same mount point.  This is accomplished by starting
 * at the end of the list and working our way backwards, stopping at the first
 * matching mount.
 */
struct vfs *
vfs_mntpoint2vfsp(const char *mp)
{
	struct vfs *vfsp;
	struct vfs *retvfsp = NULL;
	zone_t *zone = curproc->p_zone;
	struct vfs *list;

	vfs_list_read_lock();
	if (getzoneid() == GLOBAL_ZONEID) {
		/*
		 * The global zone may see filesystems in any zone.
		 */
		struct vfs search;
		search.vfs_mntpt = refstr_alloc(mp);
		search.vfs_mntix = UINT64_MAX;
		avl_index_t index;

		/*
		 * there might be several entries with the same mntpnt in the
		 * tree, only discerned by mntix. To find the last, we start
		 * with a mntix of UINT64_MAX. The search will fail. The
		 * following avl_nearest will give  us the actual last entry
		 * matching the mntpnt.
		 */
		VERIFY(avl_find(&vfs_by_mntpnt, &search, &index) == 0);
		vfsp = avl_nearest(&vfs_by_mntpnt, index, AVL_BEFORE);

		refstr_rele(search.vfs_mntpt);

		if (vfsp != NULL &&
		    strcmp(refstr_value(vfsp->vfs_mntpt), mp) == 0)
			retvfsp = vfsp;
	} else if ((list = zone->zone_vfslist) != NULL) {
		const char *mntpt;

		vfsp = list->vfs_zone_prev;
		do {
			mntpt = refstr_value(vfsp->vfs_mntpt);
			mntpt = ZONE_PATH_TRANSLATE(mntpt, zone);
			if (strcmp(mntpt, mp) == 0) {
				retvfsp = vfsp;
				break;
			}
			vfsp = vfsp->vfs_zone_prev;
		} while (vfsp != list->vfs_zone_prev);
	}
	if (retvfsp)
		VFS_HOLD(retvfsp);
	vfs_list_unlock();
	return (retvfsp);
}

/*
 * Search the vfs list for a specified vfsops.
 * if vfs entry is found then return 1, else 0.
 */
int
vfs_opsinuse(vfsops_t *ops)
{
	struct vfs *vfsp;
	int found;

	vfs_list_read_lock();
	vfsp = rootvfs;
	found = 0;
	do {
		if (vfs_getops(vfsp) == ops) {
			found = 1;
			break;
		}
		vfsp = vfsp->vfs_next;
	} while (vfsp != rootvfs);
	vfs_list_unlock();
	return (found);
}

/*
 * Allocate an entry in vfssw for a file system type
 */
struct vfssw *
allocate_vfssw(const char *type)
{
	struct vfssw *vswp;

	if (type[0] == '\0' || strlen(type) + 1 > _ST_FSTYPSZ) {
		/*
		 * The vfssw table uses the empty string to identify an
		 * available entry; we cannot add any type which has
		 * a leading NUL. The string length is limited to
		 * the size of the st_fstype array in struct stat.
		 */
		return (NULL);
	}

	ASSERT(VFSSW_WRITE_LOCKED());
	for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++)
		if (!ALLOCATED_VFSSW(vswp)) {
			vswp->vsw_name = kmem_alloc(strlen(type) + 1, KM_SLEEP);
			(void) strcpy(vswp->vsw_name, type);
			ASSERT(vswp->vsw_count == 0);
			vswp->vsw_count = 1;
			mutex_init(&vswp->vsw_lock, NULL, MUTEX_DEFAULT, NULL);
			return (vswp);
		}
	return (NULL);
}

/*
 * Impose additional layer of translation between vfstype names
 * and module names in the filesystem.
 */
static const char *
vfs_to_modname(const char *vfstype)
{
	if (strcmp(vfstype, "proc") == 0) {
		vfstype = "procfs";
	} else if (strcmp(vfstype, "fd") == 0) {
		vfstype = "fdfs";
	} else if (strncmp(vfstype, "nfs", 3) == 0) {
		vfstype = "nfs";
	}

	return (vfstype);
}

/*
 * Find a vfssw entry given a file system type name.
 * Try to autoload the filesystem if it's not found.
 * If it's installed, return the vfssw locked to prevent unloading.
 */
struct vfssw *
vfs_getvfssw(const char *type)
{
	struct vfssw *vswp;
	const char *modname;

	RLOCK_VFSSW();
	vswp = vfs_getvfsswbyname(type);
	modname = vfs_to_modname(type);

	if (rootdir == NULL) {
		/*
		 * If we haven't yet loaded the root file system, then our
		 * _init won't be called until later. Allocate vfssw entry,
		 * because mod_installfs won't be called.
		 */
		if (vswp == NULL) {
			RUNLOCK_VFSSW();
			WLOCK_VFSSW();
			if ((vswp = vfs_getvfsswbyname(type)) == NULL) {
				if ((vswp = allocate_vfssw(type)) == NULL) {
					WUNLOCK_VFSSW();
					return (NULL);
				}
			}
			WUNLOCK_VFSSW();
			RLOCK_VFSSW();
		}
		if (!VFS_INSTALLED(vswp)) {
			RUNLOCK_VFSSW();
			(void) modloadonly("fs", modname);
		} else
			RUNLOCK_VFSSW();
		return (vswp);
	}

	/*
	 * Try to load the filesystem.  Before calling modload(), we drop
	 * our lock on the VFS switch table, and pick it up after the
	 * module is loaded.  However, there is a potential race:  the
	 * module could be unloaded after the call to modload() completes
	 * but before we pick up the lock and drive on.  Therefore,
	 * we keep reloading the module until we've loaded the module
	 * _and_ we have the lock on the VFS switch table.
	 */
	while (vswp == NULL || !VFS_INSTALLED(vswp)) {
		RUNLOCK_VFSSW();
		if (modload("fs", modname) == -1)
			return (NULL);
		RLOCK_VFSSW();
		if (vswp == NULL)
			if ((vswp = vfs_getvfsswbyname(type)) == NULL)
				break;
	}
	RUNLOCK_VFSSW();

	return (vswp);
}

/*
 * Find a vfssw entry given a file system type name.
 */
struct vfssw *
vfs_getvfsswbyname(const char *type)
{
	struct vfssw *vswp;

	ASSERT(VFSSW_LOCKED());
	if (type == NULL || *type == '\0')
		return (NULL);

	for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++) {
		if (strcmp(type, vswp->vsw_name) == 0) {
			vfs_refvfssw(vswp);
			return (vswp);
		}
	}

	return (NULL);
}

/*
 * Find a vfssw entry given a set of vfsops.
 */
struct vfssw *
vfs_getvfsswbyvfsops(vfsops_t *vfsops)
{
	struct vfssw *vswp;

	RLOCK_VFSSW();
	for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++) {
		if (ALLOCATED_VFSSW(vswp) && &vswp->vsw_vfsops == vfsops) {
			vfs_refvfssw(vswp);
			RUNLOCK_VFSSW();
			return (vswp);
		}
	}
	RUNLOCK_VFSSW();

	return (NULL);
}

/*
 * Reference a vfssw entry.
 */
void
vfs_refvfssw(struct vfssw *vswp)
{

	mutex_enter(&vswp->vsw_lock);
	vswp->vsw_count++;
	mutex_exit(&vswp->vsw_lock);
}

/*
 * Unreference a vfssw entry.
 */
void
vfs_unrefvfssw(struct vfssw *vswp)
{

	mutex_enter(&vswp->vsw_lock);
	vswp->vsw_count--;
	mutex_exit(&vswp->vsw_lock);
}

int sync_timeout = 30;		/* timeout for syncing a page during panic */
int sync_timeleft;		/* portion of sync_timeout remaining */

static int sync_retries = 20;	/* number of retries when not making progress */
static int sync_triesleft;	/* portion of sync_retries remaining */

static pgcnt_t old_pgcnt, new_pgcnt;
static int new_bufcnt, old_bufcnt;

/*
 * Sync all of the mounted filesystems, and then wait for the actual i/o to
 * complete.  We wait by counting the number of dirty pages and buffers,
 * pushing them out using bio_busy() and page_busy(), and then counting again.
 * This routine is used during both the uadmin A_SHUTDOWN code as well as
 * the SYNC phase of the panic code (see comments in panic.c).  It should only
 * be used after some higher-level mechanism has quiesced the system so that
 * new writes are not being initiated while we are waiting for completion.
 *
 * To ensure finite running time, our algorithm uses two timeout mechanisms:
 * sync_timeleft (a timer implemented by the omnipresent deadman() cyclic), and
 * sync_triesleft (a progress counter used by the vfs_syncall() loop below).
 * Together these ensure that syncing completes if our i/o paths are stuck.
 * The counters are declared above so they can be found easily in the debugger.
 *
 * The sync_timeleft counter is reset by bio_busy() and page_busy() using the
 * vfs_syncprogress() subroutine whenever we make progress through the lists of
 * pages and buffers.  It is decremented and expired by the deadman() cyclic.
 * When vfs_syncall() decides it is done, we disable the deadman() counter by
 * setting sync_timeleft to zero.  This timer guards against vfs_syncall()
 * deadlocking or hanging inside of a broken filesystem or driver routine.
 *
 * The sync_triesleft counter is updated by vfs_syncall() itself.  If we make
 * sync_retries consecutive calls to bio_busy() and page_busy() without
 * decreasing either the number of dirty buffers or dirty pages below the
 * lowest count we have seen so far, we give up and return from vfs_syncall().
 *
 * Each loop iteration ends with a call to delay() one second to allow time for
 * i/o completion and to permit the user time to read our progress messages.
 */
void
vfs_syncall(void)
{
	if (rootdir == NULL && !modrootloaded)
		return; /* panic during boot - no filesystems yet */

	printf("syncing file systems...");
	vfs_syncprogress();
	sync();

	vfs_syncprogress();
	sync_triesleft = sync_retries;

	old_bufcnt = new_bufcnt = INT_MAX;
	old_pgcnt = new_pgcnt = ULONG_MAX;

	while (sync_triesleft > 0) {
		old_bufcnt = MIN(old_bufcnt, new_bufcnt);
		old_pgcnt = MIN(old_pgcnt, new_pgcnt);

		new_bufcnt = bio_busy(B_TRUE);
		new_pgcnt = page_busy(B_TRUE);
		vfs_syncprogress();

		if (new_bufcnt == 0 && new_pgcnt == 0)
			break;

		if (new_bufcnt < old_bufcnt || new_pgcnt < old_pgcnt)
			sync_triesleft = sync_retries;
		else
			sync_triesleft--;

		if (new_bufcnt)
			printf(" [%d]", new_bufcnt);
		if (new_pgcnt)
			printf(" %lu", new_pgcnt);

		delay(hz);
	}

	if (new_bufcnt != 0 || new_pgcnt != 0)
		printf(" done (not all i/o completed)\n");
	else
		printf(" done\n");

	sync_timeleft = 0;
	delay(hz);
}

/*
 * If we are in the middle of the sync phase of panic, reset sync_timeleft to
 * sync_timeout to indicate that we are making progress and the deadman()
 * omnipresent cyclic should not yet time us out.  Note that it is safe to
 * store to sync_timeleft here since the deadman() is firing at high-level
 * on top of us.  If we are racing with the deadman(), either the deadman()
 * will decrement the old value and then we will reset it, or we will
 * reset it and then the deadman() will immediately decrement it.  In either
 * case, correct behavior results.
 */
void
vfs_syncprogress(void)
{
	if (panicstr)
		sync_timeleft = sync_timeout;
}

/*
 * Map VFS flags to statvfs flags.  These shouldn't really be separate
 * flags at all.
 */
uint_t
vf_to_stf(uint_t vf)
{
	uint_t stf = 0;

	if (vf & VFS_RDONLY)
		stf |= ST_RDONLY;
	if (vf & VFS_NOSETUID)
		stf |= ST_NOSUID;
	if (vf & VFS_NOTRUNC)
		stf |= ST_NOTRUNC;

	return (stf);
}

/*
 * Entries for (illegal) fstype 0.
 */
/* ARGSUSED */
int
vfsstray_sync(struct vfs *vfsp, short arg, struct cred *cr)
{
	cmn_err(CE_PANIC, "stray vfs operation");
	return (0);
}

/*
 * Entries for (illegal) fstype 0.
 */
int
vfsstray(void)
{
	cmn_err(CE_PANIC, "stray vfs operation");
	return (0);
}

/*
 * Support for dealing with forced UFS unmount and its interaction with
 * LOFS. Could be used by any filesystem.
 * See bug 1203132.
 */
int
vfs_EIO(void)
{
	return (EIO);
}

/*
 * We've gotta define the op for sync separately, since the compiler gets
 * confused if we mix and match ANSI and normal style prototypes when
 * a "short" argument is present and spits out a warning.
 */
/*ARGSUSED*/
int
vfs_EIO_sync(struct vfs *vfsp, short arg, struct cred *cr)
{
	return (EIO);
}

vfs_t EIO_vfs;
vfsops_t *EIO_vfsops;

/*
 * Called from startup() to initialize all loaded vfs's
 */
void
vfsinit(void)
{
	struct vfssw *vswp;
	int error;
	extern int vopstats_enabled;
	extern void vopstats_startup();

	static const fs_operation_def_t EIO_vfsops_template[] = {
		VFSNAME_MOUNT,		{ .error = vfs_EIO },
		VFSNAME_UNMOUNT,	{ .error = vfs_EIO },
		VFSNAME_ROOT,		{ .error = vfs_EIO },
		VFSNAME_STATVFS,	{ .error = vfs_EIO },
		VFSNAME_SYNC, 		{ .vfs_sync = vfs_EIO_sync },
		VFSNAME_VGET,		{ .error = vfs_EIO },
		VFSNAME_MOUNTROOT,	{ .error = vfs_EIO },
		VFSNAME_FREEVFS,	{ .error = vfs_EIO },
		VFSNAME_VNSTATE,	{ .error = vfs_EIO },
		NULL, NULL
	};

	static const fs_operation_def_t stray_vfsops_template[] = {
		VFSNAME_MOUNT,		{ .error = vfsstray },
		VFSNAME_UNMOUNT,	{ .error = vfsstray },
		VFSNAME_ROOT,		{ .error = vfsstray },
		VFSNAME_STATVFS,	{ .error = vfsstray },
		VFSNAME_SYNC, 		{ .vfs_sync = vfsstray_sync },
		VFSNAME_VGET,		{ .error = vfsstray },
		VFSNAME_MOUNTROOT,	{ .error = vfsstray },
		VFSNAME_FREEVFS,	{ .error = vfsstray },
		VFSNAME_VNSTATE,	{ .error = vfsstray },
		NULL, NULL
	};

	/* Create vfs cache */
	vfs_cache = kmem_cache_create("vfs_cache", sizeof (struct vfs),
	    sizeof (uintptr_t), NULL, NULL, NULL, NULL, NULL, 0);

	/* Initialize the vnode cache (file systems may use it during init). */
	vn_create_cache();

	/* Setup event monitor framework */
	fem_init();

	/* Initialize the dummy stray file system type. */
	error = vfs_setfsops(0, stray_vfsops_template, NULL);

	/* Initialize the dummy EIO file system. */
	error = vfs_makefsops(EIO_vfsops_template, &EIO_vfsops);
	if (error != 0) {
		cmn_err(CE_WARN, "vfsinit: bad EIO vfs ops template");
		/* Shouldn't happen, but not bad enough to panic */
	}

	VFS_INIT(&EIO_vfs, EIO_vfsops, (caddr_t)NULL);

	/*
	 * Default EIO_vfs.vfs_flag to VFS_UNMOUNTED so a lookup
	 * on this vfs can immediately notice it's invalid.
	 */
	EIO_vfs.vfs_flag |= VFS_UNMOUNTED;

	/*
	 * Call the init routines of non-loadable filesystems only.
	 * Filesystems which are loaded as separate modules will be
	 * initialized by the module loading code instead.
	 */

	for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++) {
		RLOCK_VFSSW();
		if (vswp->vsw_init != NULL)
			(*vswp->vsw_init)(vswp - vfssw, vswp->vsw_name);
		RUNLOCK_VFSSW();
	}

	vopstats_startup();

	if (vopstats_enabled) {
		/* EIO_vfs can collect stats, but we don't retrieve them */
		initialize_vopstats(&EIO_vfs.vfs_vopstats);
		EIO_vfs.vfs_fstypevsp = NULL;
		EIO_vfs.vfs_vskap = NULL;
		EIO_vfs.vfs_flag |= VFS_STATS;
	}

	xattr_init();

	reparse_point_init();
}

vfs_t *
vfs_alloc(int kmflag)
{
	vfs_t *vfsp;

	vfsp = kmem_cache_alloc(vfs_cache, kmflag);

	/*
	 * Do the simplest initialization here.
	 * Everything else gets done in vfs_init()
	 */
	bzero(vfsp, sizeof (vfs_t));
	return (vfsp);
}

void
vfs_free(vfs_t *vfsp)
{
	/*
	 * One would be tempted to assert that "vfsp->vfs_count == 0".
	 * The problem is that this gets called out of domount() with
	 * a partially initialized vfs and a vfs_count of 1.  This is
	 * also called from vfs_rele() with a vfs_count of 0.  We can't
	 * call VFS_RELE() from domount() if VFS_MOUNT() hasn't successfully
	 * returned.  This is because VFS_MOUNT() fully initializes the
	 * vfs structure and its associated data.  VFS_RELE() will call
	 * VFS_FREEVFS() which may panic the system if the data structures
	 * aren't fully initialized from a successful VFS_MOUNT()).
	 */

	/* If FEM was in use, make sure everything gets cleaned up */
	if (vfsp->vfs_femhead) {
		ASSERT(vfsp->vfs_femhead->femh_list == NULL);
		mutex_destroy(&vfsp->vfs_femhead->femh_lock);
		kmem_free(vfsp->vfs_femhead, sizeof (*(vfsp->vfs_femhead)));
		vfsp->vfs_femhead = NULL;
	}

	if (vfsp->vfs_implp)
		vfsimpl_teardown(vfsp);
	sema_destroy(&vfsp->vfs_reflock);
	kmem_cache_free(vfs_cache, vfsp);
}

/*
 * Increments the vfs reference count by one atomically.
 */
void
vfs_hold(vfs_t *vfsp)
{
	atomic_inc_32(&vfsp->vfs_count);
	ASSERT(vfsp->vfs_count != 0);
}

/*
 * Decrements the vfs reference count by one atomically. When
 * vfs reference count becomes zero, it calls the file system
 * specific vfs_freevfs() to free up the resources.
 */
void
vfs_rele(vfs_t *vfsp)
{
	ASSERT(vfsp->vfs_count != 0);
	if (atomic_dec_32_nv(&vfsp->vfs_count) == 0) {
		VFS_FREEVFS(vfsp);
		lofi_remove(vfsp);
		if (vfsp->vfs_zone)
			zone_rele_ref(&vfsp->vfs_implp->vi_zone_ref,
			    ZONE_REF_VFS);
		vfs_freemnttab(vfsp);
		vfs_free(vfsp);
	}
}

/*
 * Generic operations vector support.
 *
 * This is used to build operations vectors for both the vfs and vnode.
 * It's normally called only when a file system is loaded.
 *
 * There are many possible algorithms for this, including the following:
 *
 *   (1) scan the list of known operations; for each, see if the file system
 *       includes an entry for it, and fill it in as appropriate.
 *
 *   (2) set up defaults for all known operations.  scan the list of ops
 *       supplied by the file system; for each which is both supplied and
 *       known, fill it in.
 *
 *   (3) sort the lists of known ops & supplied ops; scan the list, filling
 *       in entries as we go.
 *
 * we choose (1) for simplicity, and because performance isn't critical here.
 * note that (2) could be sped up using a precomputed hash table on known ops.
 * (3) could be faster than either, but only if the lists were very large or
 * supplied in sorted order.
 *
 */

int
fs_build_vector(void *vector, int *unused_ops,
    const fs_operation_trans_def_t *translation,
    const fs_operation_def_t *operations)
{
	int i, num_trans, num_ops, used;

	/*
	 * Count the number of translations and the number of supplied
	 * operations.
	 */

	{
		const fs_operation_trans_def_t *p;

		for (num_trans = 0, p = translation;
		    p->name != NULL;
		    num_trans++, p++)
			;
	}

	{
		const fs_operation_def_t *p;

		for (num_ops = 0, p = operations;
		    p->name != NULL;
		    num_ops++, p++)
			;
	}

	/* Walk through each operation known to our caller.  There will be */
	/* one entry in the supplied "translation table" for each. */

	used = 0;

	for (i = 0; i < num_trans; i++) {
		int j, found;
		char *curname;
		fs_generic_func_p result;
		fs_generic_func_p *location;

		curname = translation[i].name;

		/* Look for a matching operation in the list supplied by the */
		/* file system. */

		found = 0;

		for (j = 0; j < num_ops; j++) {
			if (strcmp(operations[j].name, curname) == 0) {
				used++;
				found = 1;
				break;
			}
		}

		/*
		 * If the file system is using a "placeholder" for default
		 * or error functions, grab the appropriate function out of
		 * the translation table.  If the file system didn't supply
		 * this operation at all, use the default function.
		 */

		if (found) {
			result = operations[j].func.fs_generic;
			if (result == fs_default) {
				result = translation[i].defaultFunc;
			} else if (result == fs_error) {
				result = translation[i].errorFunc;
			} else if (result == NULL) {
				/* Null values are PROHIBITED */
				return (EINVAL);
			}
		} else {
			result = translation[i].defaultFunc;
		}

		/* Now store the function into the operations vector. */

		location = (fs_generic_func_p *)
		    (((char *)vector) + translation[i].offset);

		*location = result;
	}

	*unused_ops = num_ops - used;

	return (0);
}

/* Placeholder functions, should never be called. */

int
fs_error(void)
{
	cmn_err(CE_PANIC, "fs_error called");
	return (0);
}

int
fs_default(void)
{
	cmn_err(CE_PANIC, "fs_default called");
	return (0);
}

#ifdef __sparc

/*
 * Part of the implementation of booting off a mirrored root
 * involves a change of dev_t for the root device.  To
 * accomplish this, first remove the existing hash table
 * entry for the root device, convert to the new dev_t,
 * then re-insert in the hash table at the head of the list.
 */
void
vfs_root_redev(vfs_t *vfsp, dev_t ndev, int fstype)
{
	vfs_list_lock();

	vfs_hash_remove(vfsp);

	vfsp->vfs_dev = ndev;
	vfs_make_fsid(&vfsp->vfs_fsid, ndev, fstype);

	vfs_hash_add(vfsp, 1);

	vfs_list_unlock();
}

#else /* x86 NEWBOOT */

#if defined(__x86)
extern int hvmboot_rootconf();
#endif /* __x86 */

extern ib_boot_prop_t *iscsiboot_prop;

int
rootconf()
{
	int error;
	struct vfssw *vsw;
	extern void pm_init();
	char *fstyp, *fsmod;
	int ret = -1;

	getrootfs(&fstyp, &fsmod);

#if defined(__x86)
	/*
	 * hvmboot_rootconf() is defined in the hvm_bootstrap misc module,
	 * which lives in /platform/i86hvm, and hence is only available when
	 * booted in an x86 hvm environment.  If the hvm_bootstrap misc module
	 * is not available then the modstub for this function will return 0.
	 * If the hvm_bootstrap misc module is available it will be loaded
	 * and hvmboot_rootconf() will be invoked.
	 */
	if (error = hvmboot_rootconf())
		return (error);
#endif /* __x86 */

	if (error = clboot_rootconf())
		return (error);

	if (modload("fs", fsmod) == -1)
		panic("Cannot _init %s module", fsmod);

	RLOCK_VFSSW();
	vsw = vfs_getvfsswbyname(fstyp);
	RUNLOCK_VFSSW();
	if (vsw == NULL) {
		cmn_err(CE_CONT, "Cannot find %s filesystem\n", fstyp);
		return (ENXIO);
	}
	VFS_INIT(rootvfs, &vsw->vsw_vfsops, 0);
	VFS_HOLD(rootvfs);

	/* always mount readonly first */
	rootvfs->vfs_flag |= VFS_RDONLY;

	pm_init();

	if (netboot && iscsiboot_prop) {
		cmn_err(CE_WARN, "NFS boot and iSCSI boot"
		    " shouldn't happen in the same time");
		return (EINVAL);
	}

	if (netboot || iscsiboot_prop) {
		ret = strplumb();
		if (ret != 0) {
			cmn_err(CE_WARN, "Cannot plumb network device %d", ret);
			return (EFAULT);
		}
	}

	if ((ret == 0) && iscsiboot_prop) {
		ret = modload("drv", "iscsi");
		/* -1 indicates fail */
		if (ret == -1) {
			cmn_err(CE_WARN, "Failed to load iscsi module");
			iscsi_boot_prop_free();
			return (EINVAL);
		} else {
			if (!i_ddi_attach_pseudo_node("iscsi")) {
				cmn_err(CE_WARN,
				    "Failed to attach iscsi driver");
				iscsi_boot_prop_free();
				return (ENODEV);
			}
		}
	}

	error = VFS_MOUNTROOT(rootvfs, ROOT_INIT);
	vfs_unrefvfssw(vsw);
	rootdev = rootvfs->vfs_dev;

	if (error)
		cmn_err(CE_CONT, "Cannot mount root on %s fstype %s\n",
		    rootfs.bo_name, fstyp);
	else
		cmn_err(CE_CONT, "?root on %s fstype %s\n",
		    rootfs.bo_name, fstyp);
	return (error);
}

/*
 * XXX this is called by nfs only and should probably be removed
 * If booted with ASKNAME, prompt on the console for a filesystem
 * name and return it.
 */
void
getfsname(char *askfor, char *name, size_t namelen)
{
	if (boothowto & RB_ASKNAME) {
		printf("%s name: ", askfor);
		console_gets(name, namelen);
	}
}

/*
 * Init the root filesystem type (rootfs.bo_fstype) from the "fstype"
 * property.
 *
 * Filesystem types starting with the prefix "nfs" are diskless clients;
 * init the root filename name (rootfs.bo_name), too.
 *
 * If we are booting via NFS we currently have these options:
 *	nfs -	dynamically choose NFS V2, V3, or V4 (default)
 *	nfs2 -	force NFS V2
 *	nfs3 -	force NFS V3
 *	nfs4 -	force NFS V4
 * Because we need to maintain backward compatibility with the naming
 * convention that the NFS V2 filesystem name is "nfs" (see vfs_conf.c)
 * we need to map "nfs" => "nfsdyn" and "nfs2" => "nfs".  The dynamic
 * nfs module will map the type back to either "nfs", "nfs3", or "nfs4".
 * This is only for root filesystems, all other uses will expect
 * that "nfs" == NFS V2.
 */
static void
getrootfs(char **fstypp, char **fsmodp)
{
	extern char *strplumb_get_netdev_path(void);
	char *propstr = NULL;

	/*
	 * Check fstype property; for diskless it should be one of "nfs",
	 * "nfs2", "nfs3" or "nfs4".
	 */
	if (ddi_prop_lookup_string(DDI_DEV_T_ANY, ddi_root_node(),
	    DDI_PROP_DONTPASS, "fstype", &propstr)
	    == DDI_SUCCESS) {
		(void) strncpy(rootfs.bo_fstype, propstr, BO_MAXFSNAME);
		ddi_prop_free(propstr);

	/*
	 * if the boot property 'fstype' is not set, but 'zfs-bootfs' is set,
	 * assume the type of this root filesystem is 'zfs'.
	 */
	} else if (ddi_prop_lookup_string(DDI_DEV_T_ANY, ddi_root_node(),
	    DDI_PROP_DONTPASS, "zfs-bootfs", &propstr)
	    == DDI_SUCCESS) {
		(void) strncpy(rootfs.bo_fstype, "zfs", BO_MAXFSNAME);
		ddi_prop_free(propstr);
	}

	if (strncmp(rootfs.bo_fstype, "nfs", 3) != 0) {
		*fstypp = *fsmodp = rootfs.bo_fstype;
		return;
	}

	++netboot;

	if (strcmp(rootfs.bo_fstype, "nfs2") == 0)
		(void) strcpy(rootfs.bo_fstype, "nfs");
	else if (strcmp(rootfs.bo_fstype, "nfs") == 0)
		(void) strcpy(rootfs.bo_fstype, "nfsdyn");

	/*
	 * check if path to network interface is specified in bootpath
	 * or by a hypervisor domain configuration file.
	 * XXPV - enable strlumb_get_netdev_path()
	 */
	if (ddi_prop_exists(DDI_DEV_T_ANY, ddi_root_node(), DDI_PROP_DONTPASS,
	    "xpv-nfsroot")) {
		(void) strcpy(rootfs.bo_name, "/xpvd/xnf@0");
	} else if (ddi_prop_lookup_string(DDI_DEV_T_ANY, ddi_root_node(),
	    DDI_PROP_DONTPASS, "bootpath", &propstr)
	    == DDI_SUCCESS) {
		(void) strncpy(rootfs.bo_name, propstr, BO_MAXOBJNAME);
		ddi_prop_free(propstr);
	} else {
		/* attempt to determine netdev_path via boot_mac address */
		netdev_path = strplumb_get_netdev_path();
		if (netdev_path == NULL)
			panic("cannot find boot network interface");
		(void) strncpy(rootfs.bo_name, netdev_path, BO_MAXOBJNAME);
	}
	*fstypp = rootfs.bo_fstype;
	*fsmodp = "nfs";
}
#endif

/*
 * VFS feature routines
 */

#define	VFTINDEX(feature)	(((feature) >> 32) & 0xFFFFFFFF)
#define	VFTBITS(feature)	((feature) & 0xFFFFFFFFLL)

/* Register a feature in the vfs */
void
vfs_set_feature(vfs_t *vfsp, vfs_feature_t feature)
{
	/* Note that vfs_featureset[] is found in *vfsp->vfs_implp */
	if (vfsp->vfs_implp == NULL)
		return;

	vfsp->vfs_featureset[VFTINDEX(feature)] |= VFTBITS(feature);
}

void
vfs_clear_feature(vfs_t *vfsp, vfs_feature_t feature)
{
	/* Note that vfs_featureset[] is found in *vfsp->vfs_implp */
	if (vfsp->vfs_implp == NULL)
		return;
	vfsp->vfs_featureset[VFTINDEX(feature)] &= VFTBITS(~feature);
}

/*
 * Query a vfs for a feature.
 * Returns 1 if feature is present, 0 if not
 */
int
vfs_has_feature(vfs_t *vfsp, vfs_feature_t feature)
{
	int	ret = 0;

	/* Note that vfs_featureset[] is found in *vfsp->vfs_implp */
	if (vfsp->vfs_implp == NULL)
		return (ret);

	if (vfsp->vfs_featureset[VFTINDEX(feature)] & VFTBITS(feature))
		ret = 1;

	return (ret);
}

/*
 * Propagate feature set from one vfs to another
 */
void
vfs_propagate_features(vfs_t *from, vfs_t *to)
{
	int i;

	if (to->vfs_implp == NULL || from->vfs_implp == NULL)
		return;

	for (i = 1; i <= to->vfs_featureset[0]; i++) {
		to->vfs_featureset[i] = from->vfs_featureset[i];
	}
}

#define	LOFINODE_PATH "/dev/lofi/%d"

/*
 * Return the vnode for the lofi node if there's a lofi mount in place.
 * Returns -1 when there's no lofi node, 0 on success, and > 0 on
 * failure.
 */
int
vfs_get_lofi(vfs_t *vfsp, vnode_t **vpp)
{
	char *path = NULL;
	int strsize;
	int err;

	if (vfsp->vfs_lofi_minor == 0) {
		*vpp = NULL;
		return (-1);
	}

	strsize = snprintf(NULL, 0, LOFINODE_PATH, vfsp->vfs_lofi_minor);
	path = kmem_alloc(strsize + 1, KM_SLEEP);
	(void) snprintf(path, strsize + 1, LOFINODE_PATH, vfsp->vfs_lofi_minor);

	/*
	 * We may be inside a zone, so we need to use the /dev path, but
	 * it's created asynchronously, so we wait here.
	 */
	for (;;) {
		err = lookupname(path, UIO_SYSSPACE, FOLLOW, NULLVPP, vpp);

		if (err != ENOENT)
			break;

		if ((err = delay_sig(hz / 8)) == EINTR)
			break;
	}

	if (err)
		*vpp = NULL;

	kmem_free(path, strsize + 1);
	return (err);
}