Index: head/sys/kern/vfs_mount.c
===================================================================
--- head/sys/kern/vfs_mount.c	(revision 324590)
+++ head/sys/kern/vfs_mount.c	(revision 324591)
@@ -1,2005 +1,1982 @@
 /*-
  * Copyright (c) 1999-2004 Poul-Henning Kamp
  * Copyright (c) 1999 Michael Smith
  * Copyright (c) 1989, 1993
  *	The Regents of the University of California.  All rights reserved.
  * (c) UNIX System Laboratories, Inc.
  * All or some portions of this file are derived from material licensed
  * to the University of California by American Telephone and Telegraph
  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  * the permission of UNIX System Laboratories, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/conf.h>
 #include <sys/fcntl.h>
 #include <sys/jail.h>
 #include <sys/kernel.h>
 #include <sys/libkern.h>
 #include <sys/malloc.h>
 #include <sys/mount.h>
 #include <sys/mutex.h>
 #include <sys/namei.h>
 #include <sys/priv.h>
 #include <sys/proc.h>
 #include <sys/filedesc.h>
 #include <sys/reboot.h>
 #include <sys/sbuf.h>
 #include <sys/syscallsubr.h>
 #include <sys/sysproto.h>
 #include <sys/sx.h>
 #include <sys/sysctl.h>
 #include <sys/sysent.h>
 #include <sys/systm.h>
 #include <sys/vnode.h>
 #include <vm/uma.h>
 
 #include <geom/geom.h>
 
 #include <machine/stdarg.h>
 
 #include <security/audit/audit.h>
 #include <security/mac/mac_framework.h>
 
 #define	VFS_MOUNTARG_SIZE_MAX	(1024 * 64)
 
 static int	vfs_domount(struct thread *td, const char *fstype, char *fspath,
 		    uint64_t fsflags, struct vfsoptlist **optlist);
 static void	free_mntarg(struct mntarg *ma);
 
 static int	usermount = 0;
 SYSCTL_INT(_vfs, OID_AUTO, usermount, CTLFLAG_RW, &usermount, 0,
     "Unprivileged users may mount and unmount file systems");
 
 MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
 MALLOC_DEFINE(M_STATFS, "statfs", "statfs structure");
 static uma_zone_t mount_zone;
 
 /* List of mounted filesystems. */
 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
 
 /* For any iteration/modification of mountlist */
 struct mtx mountlist_mtx;
 MTX_SYSINIT(mountlist, &mountlist_mtx, "mountlist", MTX_DEF);
 
 /*
  * Global opts, taken by all filesystems
  */
 static const char *global_opts[] = {
 	"errmsg",
 	"fstype",
 	"fspath",
 	"ro",
 	"rw",
 	"nosuid",
 	"noexec",
 	NULL
 };
 
 static int
 mount_init(void *mem, int size, int flags)
 {
 	struct mount *mp;
 
 	mp = (struct mount *)mem;
 	mtx_init(&mp->mnt_mtx, "struct mount mtx", NULL, MTX_DEF);
 	mtx_init(&mp->mnt_listmtx, "struct mount vlist mtx", NULL, MTX_DEF);
 	lockinit(&mp->mnt_explock, PVFS, "explock", 0, 0);
 	return (0);
 }
 
 static void
 mount_fini(void *mem, int size)
 {
 	struct mount *mp;
 
 	mp = (struct mount *)mem;
 	lockdestroy(&mp->mnt_explock);
 	mtx_destroy(&mp->mnt_listmtx);
 	mtx_destroy(&mp->mnt_mtx);
 }
 
 static void
 vfs_mount_init(void *dummy __unused)
 {
 
 	mount_zone = uma_zcreate("Mountpoints", sizeof(struct mount), NULL,
 	    NULL, mount_init, mount_fini, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 }
 SYSINIT(vfs_mount, SI_SUB_VFS, SI_ORDER_ANY, vfs_mount_init, NULL);
 
 /*
  * ---------------------------------------------------------------------
  * Functions for building and sanitizing the mount options
  */
 
 /* Remove one mount option. */
 static void
 vfs_freeopt(struct vfsoptlist *opts, struct vfsopt *opt)
 {
 
 	TAILQ_REMOVE(opts, opt, link);
 	free(opt->name, M_MOUNT);
 	if (opt->value != NULL)
 		free(opt->value, M_MOUNT);
 	free(opt, M_MOUNT);
 }
 
 /* Release all resources related to the mount options. */
 void
 vfs_freeopts(struct vfsoptlist *opts)
 {
 	struct vfsopt *opt;
 
 	while (!TAILQ_EMPTY(opts)) {
 		opt = TAILQ_FIRST(opts);
 		vfs_freeopt(opts, opt);
 	}
 	free(opts, M_MOUNT);
 }
 
 void
 vfs_deleteopt(struct vfsoptlist *opts, const char *name)
 {
 	struct vfsopt *opt, *temp;
 
 	if (opts == NULL)
 		return;
 	TAILQ_FOREACH_SAFE(opt, opts, link, temp)  {
 		if (strcmp(opt->name, name) == 0)
 			vfs_freeopt(opts, opt);
 	}
 }
 
 static int
 vfs_isopt_ro(const char *opt)
 {
 
 	if (strcmp(opt, "ro") == 0 || strcmp(opt, "rdonly") == 0 ||
 	    strcmp(opt, "norw") == 0)
 		return (1);
 	return (0);
 }
 
 static int
 vfs_isopt_rw(const char *opt)
 {
 
 	if (strcmp(opt, "rw") == 0 || strcmp(opt, "noro") == 0)
 		return (1);
 	return (0);
 }
 
 /*
  * Check if options are equal (with or without the "no" prefix).
  */
 static int
 vfs_equalopts(const char *opt1, const char *opt2)
 {
 	char *p;
 
 	/* "opt" vs. "opt" or "noopt" vs. "noopt" */
 	if (strcmp(opt1, opt2) == 0)
 		return (1);
 	/* "noopt" vs. "opt" */
 	if (strncmp(opt1, "no", 2) == 0 && strcmp(opt1 + 2, opt2) == 0)
 		return (1);
 	/* "opt" vs. "noopt" */
 	if (strncmp(opt2, "no", 2) == 0 && strcmp(opt1, opt2 + 2) == 0)
 		return (1);
 	while ((p = strchr(opt1, '.')) != NULL &&
 	    !strncmp(opt1, opt2, ++p - opt1)) {
 		opt2 += p - opt1;
 		opt1 = p;
 		/* "foo.noopt" vs. "foo.opt" */
 		if (strncmp(opt1, "no", 2) == 0 && strcmp(opt1 + 2, opt2) == 0)
 			return (1);
 		/* "foo.opt" vs. "foo.noopt" */
 		if (strncmp(opt2, "no", 2) == 0 && strcmp(opt1, opt2 + 2) == 0)
 			return (1);
 	}
 	/* "ro" / "rdonly" / "norw" / "rw" / "noro" */
 	if ((vfs_isopt_ro(opt1) || vfs_isopt_rw(opt1)) &&
 	    (vfs_isopt_ro(opt2) || vfs_isopt_rw(opt2)))
 		return (1);
 	return (0);
 }
 
 /*
  * If a mount option is specified several times,
  * (with or without the "no" prefix) only keep
  * the last occurrence of it.
  */
 static void
 vfs_sanitizeopts(struct vfsoptlist *opts)
 {
 	struct vfsopt *opt, *opt2, *tmp;
 
 	TAILQ_FOREACH_REVERSE(opt, opts, vfsoptlist, link) {
 		opt2 = TAILQ_PREV(opt, vfsoptlist, link);
 		while (opt2 != NULL) {
 			if (vfs_equalopts(opt->name, opt2->name)) {
 				tmp = TAILQ_PREV(opt2, vfsoptlist, link);
 				vfs_freeopt(opts, opt2);
 				opt2 = tmp;
 			} else {
 				opt2 = TAILQ_PREV(opt2, vfsoptlist, link);
 			}
 		}
 	}
 }
 
 /*
  * Build a linked list of mount options from a struct uio.
  */
 int
 vfs_buildopts(struct uio *auio, struct vfsoptlist **options)
 {
 	struct vfsoptlist *opts;
 	struct vfsopt *opt;
 	size_t memused, namelen, optlen;
 	unsigned int i, iovcnt;
 	int error;
 
 	opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
 	TAILQ_INIT(opts);
 	memused = 0;
 	iovcnt = auio->uio_iovcnt;
 	for (i = 0; i < iovcnt; i += 2) {
 		namelen = auio->uio_iov[i].iov_len;
 		optlen = auio->uio_iov[i + 1].iov_len;
 		memused += sizeof(struct vfsopt) + optlen + namelen;
 		/*
 		 * Avoid consuming too much memory, and attempts to overflow
 		 * memused.
 		 */
 		if (memused > VFS_MOUNTARG_SIZE_MAX ||
 		    optlen > VFS_MOUNTARG_SIZE_MAX ||
 		    namelen > VFS_MOUNTARG_SIZE_MAX) {
 			error = EINVAL;
 			goto bad;
 		}
 
 		opt = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
 		opt->name = malloc(namelen, M_MOUNT, M_WAITOK);
 		opt->value = NULL;
 		opt->len = 0;
 		opt->pos = i / 2;
 		opt->seen = 0;
 
 		/*
 		 * Do this early, so jumps to "bad" will free the current
 		 * option.
 		 */
 		TAILQ_INSERT_TAIL(opts, opt, link);
 
 		if (auio->uio_segflg == UIO_SYSSPACE) {
 			bcopy(auio->uio_iov[i].iov_base, opt->name, namelen);
 		} else {
 			error = copyin(auio->uio_iov[i].iov_base, opt->name,
 			    namelen);
 			if (error)
 				goto bad;
 		}
 		/* Ensure names are null-terminated strings. */
 		if (namelen == 0 || opt->name[namelen - 1] != '\0') {
 			error = EINVAL;
 			goto bad;
 		}
 		if (optlen != 0) {
 			opt->len = optlen;
 			opt->value = malloc(optlen, M_MOUNT, M_WAITOK);
 			if (auio->uio_segflg == UIO_SYSSPACE) {
 				bcopy(auio->uio_iov[i + 1].iov_base, opt->value,
 				    optlen);
 			} else {
 				error = copyin(auio->uio_iov[i + 1].iov_base,
 				    opt->value, optlen);
 				if (error)
 					goto bad;
 			}
 		}
 	}
 	vfs_sanitizeopts(opts);
 	*options = opts;
 	return (0);
 bad:
 	vfs_freeopts(opts);
 	return (error);
 }
 
 /*
  * Merge the old mount options with the new ones passed
  * in the MNT_UPDATE case.
  *
  * XXX: This function will keep a "nofoo" option in the new
  * options.  E.g, if the option's canonical name is "foo",
  * "nofoo" ends up in the mount point's active options.
  */
 static void
 vfs_mergeopts(struct vfsoptlist *toopts, struct vfsoptlist *oldopts)
 {
 	struct vfsopt *opt, *new;
 
 	TAILQ_FOREACH(opt, oldopts, link) {
 		new = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
 		new->name = strdup(opt->name, M_MOUNT);
 		if (opt->len != 0) {
 			new->value = malloc(opt->len, M_MOUNT, M_WAITOK);
 			bcopy(opt->value, new->value, opt->len);
 		} else
 			new->value = NULL;
 		new->len = opt->len;
 		new->seen = opt->seen;
 		TAILQ_INSERT_HEAD(toopts, new, link);
 	}
 	vfs_sanitizeopts(toopts);
 }
 
 /*
  * Mount a filesystem.
  */
 #ifndef _SYS_SYSPROTO_H_
 struct nmount_args {
 	struct iovec *iovp;
 	unsigned int iovcnt;
 	int flags;
 };
 #endif
 int
 sys_nmount(struct thread *td, struct nmount_args *uap)
 {
 	struct uio *auio;
 	int error;
 	u_int iovcnt;
 	uint64_t flags;
 
 	/*
 	 * Mount flags are now 64-bits. On 32-bit archtectures only
 	 * 32-bits are passed in, but from here on everything handles
 	 * 64-bit flags correctly.
 	 */
 	flags = uap->flags;
 
 	AUDIT_ARG_FFLAGS(flags);
 	CTR4(KTR_VFS, "%s: iovp %p with iovcnt %d and flags %d", __func__,
 	    uap->iovp, uap->iovcnt, flags);
 
 	/*
 	 * Filter out MNT_ROOTFS.  We do not want clients of nmount() in
 	 * userspace to set this flag, but we must filter it out if we want
 	 * MNT_UPDATE on the root file system to work.
 	 * MNT_ROOTFS should only be set by the kernel when mounting its
 	 * root file system.
 	 */
 	flags &= ~MNT_ROOTFS;
 
 	iovcnt = uap->iovcnt;
 	/*
 	 * Check that we have an even number of iovec's
 	 * and that we have at least two options.
 	 */
 	if ((iovcnt & 1) || (iovcnt < 4)) {
 		CTR2(KTR_VFS, "%s: failed for invalid iovcnt %d", __func__,
 		    uap->iovcnt);
 		return (EINVAL);
 	}
 
 	error = copyinuio(uap->iovp, iovcnt, &auio);
 	if (error) {
 		CTR2(KTR_VFS, "%s: failed for invalid uio op with %d errno",
 		    __func__, error);
 		return (error);
 	}
 	error = vfs_donmount(td, flags, auio);
 
 	free(auio, M_IOV);
 	return (error);
 }
 
 /*
  * ---------------------------------------------------------------------
  * Various utility functions
  */
 
 void
 vfs_ref(struct mount *mp)
 {
 
 	CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
 	MNT_ILOCK(mp);
 	MNT_REF(mp);
 	MNT_IUNLOCK(mp);
 }
 
 void
 vfs_rel(struct mount *mp)
 {
 
 	CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
 	MNT_ILOCK(mp);
 	MNT_REL(mp);
 	MNT_IUNLOCK(mp);
 }
 
 /*
  * Allocate and initialize the mount point struct.
  */
 struct mount *
 vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp, const char *fspath,
     struct ucred *cred)
 {
 	struct mount *mp;
 
 	mp = uma_zalloc(mount_zone, M_WAITOK);
 	bzero(&mp->mnt_startzero,
 	    __rangeof(struct mount, mnt_startzero, mnt_endzero));
 	TAILQ_INIT(&mp->mnt_nvnodelist);
 	mp->mnt_nvnodelistsize = 0;
 	TAILQ_INIT(&mp->mnt_activevnodelist);
 	mp->mnt_activevnodelistsize = 0;
 	TAILQ_INIT(&mp->mnt_tmpfreevnodelist);
 	mp->mnt_tmpfreevnodelistsize = 0;
 	mp->mnt_ref = 0;
 	(void) vfs_busy(mp, MBF_NOWAIT);
 	atomic_add_acq_int(&vfsp->vfc_refcount, 1);
 	mp->mnt_op = vfsp->vfc_vfsops;
 	mp->mnt_vfc = vfsp;
 	mp->mnt_stat.f_type = vfsp->vfc_typenum;
 	mp->mnt_gen++;
 	strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
 	mp->mnt_vnodecovered = vp;
 	mp->mnt_cred = crdup(cred);
 	mp->mnt_stat.f_owner = cred->cr_uid;
 	strlcpy(mp->mnt_stat.f_mntonname, fspath, MNAMELEN);
 	mp->mnt_iosize_max = DFLTPHYS;
 #ifdef MAC
 	mac_mount_init(mp);
 	mac_mount_create(cred, mp);
 #endif
 	arc4rand(&mp->mnt_hashseed, sizeof mp->mnt_hashseed, 0);
 	TAILQ_INIT(&mp->mnt_uppers);
 	return (mp);
 }
 
 /*
  * Destroy the mount struct previously allocated by vfs_mount_alloc().
  */
 void
 vfs_mount_destroy(struct mount *mp)
 {
 
 	MNT_ILOCK(mp);
 	mp->mnt_kern_flag |= MNTK_REFEXPIRE;
 	if (mp->mnt_kern_flag & MNTK_MWAIT) {
 		mp->mnt_kern_flag &= ~MNTK_MWAIT;
 		wakeup(mp);
 	}
 	while (mp->mnt_ref)
 		msleep(mp, MNT_MTX(mp), PVFS, "mntref", 0);
 	KASSERT(mp->mnt_ref == 0,
 	    ("%s: invalid refcount in the drain path @ %s:%d", __func__,
 	    __FILE__, __LINE__));
 	if (mp->mnt_writeopcount != 0)
 		panic("vfs_mount_destroy: nonzero writeopcount");
 	if (mp->mnt_secondary_writes != 0)
 		panic("vfs_mount_destroy: nonzero secondary_writes");
 	atomic_subtract_rel_int(&mp->mnt_vfc->vfc_refcount, 1);
 	if (!TAILQ_EMPTY(&mp->mnt_nvnodelist)) {
 		struct vnode *vp;
 
 		TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes)
 			vn_printf(vp, "dangling vnode ");
 		panic("unmount: dangling vnode");
 	}
 	KASSERT(TAILQ_EMPTY(&mp->mnt_uppers), ("mnt_uppers"));
 	if (mp->mnt_nvnodelistsize != 0)
 		panic("vfs_mount_destroy: nonzero nvnodelistsize");
 	if (mp->mnt_activevnodelistsize != 0)
 		panic("vfs_mount_destroy: nonzero activevnodelistsize");
 	if (mp->mnt_tmpfreevnodelistsize != 0)
 		panic("vfs_mount_destroy: nonzero tmpfreevnodelistsize");
 	if (mp->mnt_lockref != 0)
 		panic("vfs_mount_destroy: nonzero lock refcount");
 	MNT_IUNLOCK(mp);
 	if (mp->mnt_vnodecovered != NULL)
 		vrele(mp->mnt_vnodecovered);
 #ifdef MAC
 	mac_mount_destroy(mp);
 #endif
 	if (mp->mnt_opt != NULL)
 		vfs_freeopts(mp->mnt_opt);
 	crfree(mp->mnt_cred);
 	uma_zfree(mount_zone, mp);
 }
 
 int
 vfs_donmount(struct thread *td, uint64_t fsflags, struct uio *fsoptions)
 {
 	struct vfsoptlist *optlist;
 	struct vfsopt *opt, *tmp_opt;
 	char *fstype, *fspath, *errmsg;
 	int error, fstypelen, fspathlen, errmsg_len, errmsg_pos;
 
 	errmsg = fspath = NULL;
 	errmsg_len = fspathlen = 0;
 	errmsg_pos = -1;
 
 	error = vfs_buildopts(fsoptions, &optlist);
 	if (error)
 		return (error);
 
 	if (vfs_getopt(optlist, "errmsg", (void **)&errmsg, &errmsg_len) == 0)
 		errmsg_pos = vfs_getopt_pos(optlist, "errmsg");
 
 	/*
 	 * We need these two options before the others,
 	 * and they are mandatory for any filesystem.
 	 * Ensure they are NUL terminated as well.
 	 */
 	fstypelen = 0;
 	error = vfs_getopt(optlist, "fstype", (void **)&fstype, &fstypelen);
 	if (error || fstype[fstypelen - 1] != '\0') {
 		error = EINVAL;
 		if (errmsg != NULL)
 			strncpy(errmsg, "Invalid fstype", errmsg_len);
 		goto bail;
 	}
 	fspathlen = 0;
 	error = vfs_getopt(optlist, "fspath", (void **)&fspath, &fspathlen);
 	if (error || fspath[fspathlen - 1] != '\0') {
 		error = EINVAL;
 		if (errmsg != NULL)
 			strncpy(errmsg, "Invalid fspath", errmsg_len);
 		goto bail;
 	}
 
 	/*
 	 * We need to see if we have the "update" option
 	 * before we call vfs_domount(), since vfs_domount() has special
 	 * logic based on MNT_UPDATE.  This is very important
 	 * when we want to update the root filesystem.
 	 */
 	TAILQ_FOREACH_SAFE(opt, optlist, link, tmp_opt) {
 		if (strcmp(opt->name, "update") == 0) {
 			fsflags |= MNT_UPDATE;
 			vfs_freeopt(optlist, opt);
 		}
 		else if (strcmp(opt->name, "async") == 0)
 			fsflags |= MNT_ASYNC;
 		else if (strcmp(opt->name, "force") == 0) {
 			fsflags |= MNT_FORCE;
 			vfs_freeopt(optlist, opt);
 		}
 		else if (strcmp(opt->name, "reload") == 0) {
 			fsflags |= MNT_RELOAD;
 			vfs_freeopt(optlist, opt);
 		}
 		else if (strcmp(opt->name, "multilabel") == 0)
 			fsflags |= MNT_MULTILABEL;
 		else if (strcmp(opt->name, "noasync") == 0)
 			fsflags &= ~MNT_ASYNC;
 		else if (strcmp(opt->name, "noatime") == 0)
 			fsflags |= MNT_NOATIME;
 		else if (strcmp(opt->name, "atime") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonoatime", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "noclusterr") == 0)
 			fsflags |= MNT_NOCLUSTERR;
 		else if (strcmp(opt->name, "clusterr") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonoclusterr", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "noclusterw") == 0)
 			fsflags |= MNT_NOCLUSTERW;
 		else if (strcmp(opt->name, "clusterw") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonoclusterw", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "noexec") == 0)
 			fsflags |= MNT_NOEXEC;
 		else if (strcmp(opt->name, "exec") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonoexec", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "nosuid") == 0)
 			fsflags |= MNT_NOSUID;
 		else if (strcmp(opt->name, "suid") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonosuid", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "nosymfollow") == 0)
 			fsflags |= MNT_NOSYMFOLLOW;
 		else if (strcmp(opt->name, "symfollow") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("nonosymfollow", M_MOUNT);
 		}
 		else if (strcmp(opt->name, "noro") == 0)
 			fsflags &= ~MNT_RDONLY;
 		else if (strcmp(opt->name, "rw") == 0)
 			fsflags &= ~MNT_RDONLY;
 		else if (strcmp(opt->name, "ro") == 0)
 			fsflags |= MNT_RDONLY;
 		else if (strcmp(opt->name, "rdonly") == 0) {
 			free(opt->name, M_MOUNT);
 			opt->name = strdup("ro", M_MOUNT);
 			fsflags |= MNT_RDONLY;
 		}
 		else if (strcmp(opt->name, "suiddir") == 0)
 			fsflags |= MNT_SUIDDIR;
 		else if (strcmp(opt->name, "sync") == 0)
 			fsflags |= MNT_SYNCHRONOUS;
 		else if (strcmp(opt->name, "union") == 0)
 			fsflags |= MNT_UNION;
 		else if (strcmp(opt->name, "automounted") == 0) {
 			fsflags |= MNT_AUTOMOUNTED;
 			vfs_freeopt(optlist, opt);
 		}
 	}
 
 	/*
 	 * Be ultra-paranoid about making sure the type and fspath
 	 * variables will fit in our mp buffers, including the
 	 * terminating NUL.
 	 */
 	if (fstypelen > MFSNAMELEN || fspathlen > MNAMELEN) {
 		error = ENAMETOOLONG;
 		goto bail;
 	}
 
 	error = vfs_domount(td, fstype, fspath, fsflags, &optlist);
 bail:
 	/* copyout the errmsg */
 	if (errmsg_pos != -1 && ((2 * errmsg_pos + 1) < fsoptions->uio_iovcnt)
 	    && errmsg_len > 0 && errmsg != NULL) {
 		if (fsoptions->uio_segflg == UIO_SYSSPACE) {
 			bcopy(errmsg,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
 		} else {
 			copyout(errmsg,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
 			    fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
 		}
 	}
 
 	if (optlist != NULL)
 		vfs_freeopts(optlist);
 	return (error);
 }
 
 /*
  * Old mount API.
  */
 #ifndef _SYS_SYSPROTO_H_
 struct mount_args {
 	char	*type;
 	char	*path;
 	int	flags;
 	caddr_t	data;
 };
 #endif
 /* ARGSUSED */
 int
 sys_mount(struct thread *td, struct mount_args *uap)
 {
 	char *fstype;
 	struct vfsconf *vfsp = NULL;
 	struct mntarg *ma = NULL;
 	uint64_t flags;
 	int error;
 
 	/*
 	 * Mount flags are now 64-bits. On 32-bit architectures only
 	 * 32-bits are passed in, but from here on everything handles
 	 * 64-bit flags correctly.
 	 */
 	flags = uap->flags;
 
 	AUDIT_ARG_FFLAGS(flags);
 
 	/*
 	 * Filter out MNT_ROOTFS.  We do not want clients of mount() in
 	 * userspace to set this flag, but we must filter it out if we want
 	 * MNT_UPDATE on the root file system to work.
 	 * MNT_ROOTFS should only be set by the kernel when mounting its
 	 * root file system.
 	 */
 	flags &= ~MNT_ROOTFS;
 
 	fstype = malloc(MFSNAMELEN, M_TEMP, M_WAITOK);
 	error = copyinstr(uap->type, fstype, MFSNAMELEN, NULL);
 	if (error) {
 		free(fstype, M_TEMP);
 		return (error);
 	}
 
 	AUDIT_ARG_TEXT(fstype);
 	vfsp = vfs_byname_kld(fstype, td, &error);
 	free(fstype, M_TEMP);
 	if (vfsp == NULL)
 		return (ENOENT);
 	if (vfsp->vfc_vfsops->vfs_cmount == NULL)
 		return (EOPNOTSUPP);
 
 	ma = mount_argsu(ma, "fstype", uap->type, MFSNAMELEN);
 	ma = mount_argsu(ma, "fspath", uap->path, MNAMELEN);
 	ma = mount_argb(ma, flags & MNT_RDONLY, "noro");
 	ma = mount_argb(ma, !(flags & MNT_NOSUID), "nosuid");
 	ma = mount_argb(ma, !(flags & MNT_NOEXEC), "noexec");
 
 	error = vfsp->vfc_vfsops->vfs_cmount(ma, uap->data, flags);
 	return (error);
 }
 
 /*
  * vfs_domount_first(): first file system mount (not update)
  */
 static int
 vfs_domount_first(
 	struct thread *td,		/* Calling thread. */
 	struct vfsconf *vfsp,		/* File system type. */
 	char *fspath,			/* Mount path. */
 	struct vnode *vp,		/* Vnode to be covered. */
 	uint64_t fsflags,		/* Flags common to all filesystems. */
 	struct vfsoptlist **optlist	/* Options local to the filesystem. */
 	)
 {
 	struct vattr va;
 	struct mount *mp;
 	struct vnode *newdp;
 	int error;
 
 	ASSERT_VOP_ELOCKED(vp, __func__);
 	KASSERT((fsflags & MNT_UPDATE) == 0, ("MNT_UPDATE shouldn't be here"));
 
 	/*
 	 * If the user is not root, ensure that they own the directory
 	 * onto which we are attempting to mount.
 	 */
 	error = VOP_GETATTR(vp, &va, td->td_ucred);
 	if (error == 0 && va.va_uid != td->td_ucred->cr_uid)
 		error = priv_check_cred(td->td_ucred, PRIV_VFS_ADMIN, 0);
 	if (error == 0)
 		error = vinvalbuf(vp, V_SAVE, 0, 0);
 	if (error == 0 && vp->v_type != VDIR)
 		error = ENOTDIR;
 	if (error == 0) {
 		VI_LOCK(vp);
 		if ((vp->v_iflag & VI_MOUNT) == 0 && vp->v_mountedhere == NULL)
 			vp->v_iflag |= VI_MOUNT;
 		else
 			error = EBUSY;
 		VI_UNLOCK(vp);
 	}
 	if (error != 0) {
 		vput(vp);
 		return (error);
 	}
 	VOP_UNLOCK(vp, 0);
 
 	/* Allocate and initialize the filesystem. */
 	mp = vfs_mount_alloc(vp, vfsp, fspath, td->td_ucred);
 	/* XXXMAC: pass to vfs_mount_alloc? */
 	mp->mnt_optnew = *optlist;
 	/* Set the mount level flags. */
 	mp->mnt_flag = (fsflags & (MNT_UPDATEMASK | MNT_ROOTFS | MNT_RDONLY));
 
 	/*
 	 * Mount the filesystem.
 	 * XXX The final recipients of VFS_MOUNT just overwrite the ndp they
 	 * get.  No freeing of cn_pnbuf.
 	 */
 	error = VFS_MOUNT(mp);
 	if (error != 0) {
 		vfs_unbusy(mp);
 		mp->mnt_vnodecovered = NULL;
 		vfs_mount_destroy(mp);
 		VI_LOCK(vp);
 		vp->v_iflag &= ~VI_MOUNT;
 		VI_UNLOCK(vp);
 		vrele(vp);
 		return (error);
 	}
 
 	if (mp->mnt_opt != NULL)
 		vfs_freeopts(mp->mnt_opt);
 	mp->mnt_opt = mp->mnt_optnew;
 	*optlist = NULL;
 	(void)VFS_STATFS(mp, &mp->mnt_stat);
 
 	/*
 	 * Prevent external consumers of mount options from reading mnt_optnew.
 	 */
 	mp->mnt_optnew = NULL;
 
 	MNT_ILOCK(mp);
 	if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
 	    (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
 		mp->mnt_kern_flag |= MNTK_ASYNC;
 	else
 		mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 	cache_purge(vp);
 	VI_LOCK(vp);
 	vp->v_iflag &= ~VI_MOUNT;
 	VI_UNLOCK(vp);
 	vp->v_mountedhere = mp;
 	/* Place the new filesystem at the end of the mount list. */
 	mtx_lock(&mountlist_mtx);
 	TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
 	mtx_unlock(&mountlist_mtx);
 	vfs_event_signal(NULL, VQ_MOUNT, 0);
 	if (VFS_ROOT(mp, LK_EXCLUSIVE, &newdp))
 		panic("mount: lost mount");
 	VOP_UNLOCK(vp, 0);
 	EVENTHANDLER_INVOKE(vfs_mounted, mp, newdp, td);
 	VOP_UNLOCK(newdp, 0);
 	mountcheckdirs(vp, newdp);
 	vrele(newdp);
 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
 		vfs_allocate_syncvnode(mp);
 	vfs_unbusy(mp);
 	return (0);
 }
 
 /*
  * vfs_domount_update(): update of mounted file system
  */
 static int
 vfs_domount_update(
 	struct thread *td,		/* Calling thread. */
 	struct vnode *vp,		/* Mount point vnode. */
 	uint64_t fsflags,		/* Flags common to all filesystems. */
 	struct vfsoptlist **optlist	/* Options local to the filesystem. */
 	)
 {
 	struct export_args export;
 	void *bufp;
 	struct mount *mp;
 	int error, export_error, len;
 	uint64_t flag;
 
 	ASSERT_VOP_ELOCKED(vp, __func__);
 	KASSERT((fsflags & MNT_UPDATE) != 0, ("MNT_UPDATE should be here"));
 	mp = vp->v_mount;
 
 	if ((vp->v_vflag & VV_ROOT) == 0) {
 		if (vfs_copyopt(*optlist, "export", &export, sizeof(export))
 		    == 0)
 			error = EXDEV;
 		else
 			error = EINVAL;
 		vput(vp);
 		return (error);
 	}
 
 	/*
 	 * We only allow the filesystem to be reloaded if it
 	 * is currently mounted read-only.
 	 */
 	flag = mp->mnt_flag;
 	if ((fsflags & MNT_RELOAD) != 0 && (flag & MNT_RDONLY) == 0) {
 		vput(vp);
 		return (EOPNOTSUPP);	/* Needs translation */
 	}
 	/*
 	 * Only privileged root, or (if MNT_USER is set) the user that
 	 * did the original mount is permitted to update it.
 	 */
 	error = vfs_suser(mp, td);
 	if (error != 0) {
 		vput(vp);
 		return (error);
 	}
 	if (vfs_busy(mp, MBF_NOWAIT)) {
 		vput(vp);
 		return (EBUSY);
 	}
 	VI_LOCK(vp);
 	if ((vp->v_iflag & VI_MOUNT) != 0 || vp->v_mountedhere != NULL) {
 		VI_UNLOCK(vp);
 		vfs_unbusy(mp);
 		vput(vp);
 		return (EBUSY);
 	}
 	vp->v_iflag |= VI_MOUNT;
 	VI_UNLOCK(vp);
 	VOP_UNLOCK(vp, 0);
 
 	MNT_ILOCK(mp);
 	if ((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0) {
 		MNT_IUNLOCK(mp);
 		error = EBUSY;
 		goto end;
 	}
 	mp->mnt_flag &= ~MNT_UPDATEMASK;
 	mp->mnt_flag |= fsflags & (MNT_RELOAD | MNT_FORCE | MNT_UPDATE |
 	    MNT_SNAPSHOT | MNT_ROOTFS | MNT_UPDATEMASK | MNT_RDONLY);
 	if ((mp->mnt_flag & MNT_ASYNC) == 0)
 		mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	mp->mnt_optnew = *optlist;
 	vfs_mergeopts(mp->mnt_optnew, mp->mnt_opt);
 
 	/*
 	 * Mount the filesystem.
 	 * XXX The final recipients of VFS_MOUNT just overwrite the ndp they
 	 * get.  No freeing of cn_pnbuf.
 	 */
 	error = VFS_MOUNT(mp);
 
 	export_error = 0;
 	/* Process the export option. */
 	if (error == 0 && vfs_getopt(mp->mnt_optnew, "export", &bufp,
 	    &len) == 0) {
 		/* Assume that there is only 1 ABI for each length. */
 		switch (len) {
 		case (sizeof(struct oexport_args)):
 			bzero(&export, sizeof(export));
 			/* FALLTHROUGH */
 		case (sizeof(export)):
 			bcopy(bufp, &export, len);
 			export_error = vfs_export(mp, &export);
 			break;
 		default:
 			export_error = EINVAL;
 			break;
 		}
 	}
 
 	MNT_ILOCK(mp);
 	if (error == 0) {
 		mp->mnt_flag &=	~(MNT_UPDATE | MNT_RELOAD | MNT_FORCE |
 		    MNT_SNAPSHOT);
 	} else {
 		/*
 		 * If we fail, restore old mount flags. MNT_QUOTA is special,
 		 * because it is not part of MNT_UPDATEMASK, but it could have
 		 * changed in the meantime if quotactl(2) was called.
 		 * All in all we want current value of MNT_QUOTA, not the old
 		 * one.
 		 */
 		mp->mnt_flag = (mp->mnt_flag & MNT_QUOTA) | (flag & ~MNT_QUOTA);
 	}
 	if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
 	    (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
 		mp->mnt_kern_flag |= MNTK_ASYNC;
 	else
 		mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 
 	if (error != 0)
 		goto end;
 
 	if (mp->mnt_opt != NULL)
 		vfs_freeopts(mp->mnt_opt);
 	mp->mnt_opt = mp->mnt_optnew;
 	*optlist = NULL;
 	(void)VFS_STATFS(mp, &mp->mnt_stat);
 	/*
 	 * Prevent external consumers of mount options from reading
 	 * mnt_optnew.
 	 */
 	mp->mnt_optnew = NULL;
 
 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
 		vfs_allocate_syncvnode(mp);
 	else
 		vfs_deallocate_syncvnode(mp);
 end:
 	vfs_unbusy(mp);
 	VI_LOCK(vp);
 	vp->v_iflag &= ~VI_MOUNT;
 	VI_UNLOCK(vp);
 	vrele(vp);
 	return (error != 0 ? error : export_error);
 }
 
 /*
  * vfs_domount(): actually attempt a filesystem mount.
  */
 static int
 vfs_domount(
 	struct thread *td,		/* Calling thread. */
 	const char *fstype,		/* Filesystem type. */
 	char *fspath,			/* Mount path. */
 	uint64_t fsflags,		/* Flags common to all filesystems. */
 	struct vfsoptlist **optlist	/* Options local to the filesystem. */
 	)
 {
 	struct vfsconf *vfsp;
 	struct nameidata nd;
 	struct vnode *vp;
 	char *pathbuf;
 	int error;
 
 	/*
 	 * Be ultra-paranoid about making sure the type and fspath
 	 * variables will fit in our mp buffers, including the
 	 * terminating NUL.
 	 */
 	if (strlen(fstype) >= MFSNAMELEN || strlen(fspath) >= MNAMELEN)
 		return (ENAMETOOLONG);
 
 	if (jailed(td->td_ucred) || usermount == 0) {
 		if ((error = priv_check(td, PRIV_VFS_MOUNT)) != 0)
 			return (error);
 	}
 
 	/*
 	 * Do not allow NFS export or MNT_SUIDDIR by unprivileged users.
 	 */
 	if (fsflags & MNT_EXPORTED) {
 		error = priv_check(td, PRIV_VFS_MOUNT_EXPORTED);
 		if (error)
 			return (error);
 	}
 	if (fsflags & MNT_SUIDDIR) {
 		error = priv_check(td, PRIV_VFS_MOUNT_SUIDDIR);
 		if (error)
 			return (error);
 	}
 	/*
 	 * Silently enforce MNT_NOSUID and MNT_USER for unprivileged users.
 	 */
 	if ((fsflags & (MNT_NOSUID | MNT_USER)) != (MNT_NOSUID | MNT_USER)) {
 		if (priv_check(td, PRIV_VFS_MOUNT_NONUSER) != 0)
 			fsflags |= MNT_NOSUID | MNT_USER;
 	}
 
 	/* Load KLDs before we lock the covered vnode to avoid reversals. */
 	vfsp = NULL;
 	if ((fsflags & MNT_UPDATE) == 0) {
 		/* Don't try to load KLDs if we're mounting the root. */
 		if (fsflags & MNT_ROOTFS)
 			vfsp = vfs_byname(fstype);
 		else
 			vfsp = vfs_byname_kld(fstype, td, &error);
 		if (vfsp == NULL)
 			return (ENODEV);
 		if (jailed(td->td_ucred) && !(vfsp->vfc_flags & VFCF_JAIL))
 			return (EPERM);
 	}
 
 	/*
 	 * Get vnode to be covered or mount point's vnode in case of MNT_UPDATE.
 	 */
 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
 	    UIO_SYSSPACE, fspath, td);
 	error = namei(&nd);
 	if (error != 0)
 		return (error);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	vp = nd.ni_vp;
 	if ((fsflags & MNT_UPDATE) == 0) {
 		pathbuf = malloc(MNAMELEN, M_TEMP, M_WAITOK);
 		strcpy(pathbuf, fspath);
 		error = vn_path_to_global_path(td, vp, pathbuf, MNAMELEN);
 		/* debug.disablefullpath == 1 results in ENODEV */
 		if (error == 0 || error == ENODEV) {
 			error = vfs_domount_first(td, vfsp, pathbuf, vp,
 			    fsflags, optlist);
 		}
 		free(pathbuf, M_TEMP);
 	} else
 		error = vfs_domount_update(td, vp, fsflags, optlist);
 
 	return (error);
 }
 
 /*
  * Unmount a filesystem.
  *
  * Note: unmount takes a path to the vnode mounted on as argument, not
  * special file (as before).
  */
 #ifndef _SYS_SYSPROTO_H_
 struct unmount_args {
 	char	*path;
 	int	flags;
 };
 #endif
 /* ARGSUSED */
 int
 sys_unmount(struct thread *td, struct unmount_args *uap)
 {
 	struct nameidata nd;
 	struct mount *mp;
 	char *pathbuf;
 	int error, id0, id1;
 
 	AUDIT_ARG_VALUE(uap->flags);
 	if (jailed(td->td_ucred) || usermount == 0) {
 		error = priv_check(td, PRIV_VFS_UNMOUNT);
 		if (error)
 			return (error);
 	}
 
 	pathbuf = malloc(MNAMELEN, M_TEMP, M_WAITOK);
 	error = copyinstr(uap->path, pathbuf, MNAMELEN, NULL);
 	if (error) {
 		free(pathbuf, M_TEMP);
 		return (error);
 	}
 	if (uap->flags & MNT_BYFSID) {
 		AUDIT_ARG_TEXT(pathbuf);
 		/* Decode the filesystem ID. */
 		if (sscanf(pathbuf, "FSID:%d:%d", &id0, &id1) != 2) {
 			free(pathbuf, M_TEMP);
 			return (EINVAL);
 		}
 
 		mtx_lock(&mountlist_mtx);
 		TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
 			if (mp->mnt_stat.f_fsid.val[0] == id0 &&
 			    mp->mnt_stat.f_fsid.val[1] == id1) {
 				vfs_ref(mp);
 				break;
 			}
 		}
 		mtx_unlock(&mountlist_mtx);
 	} else {
 		/*
 		 * Try to find global path for path argument.
 		 */
 		NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
 		    UIO_SYSSPACE, pathbuf, td);
 		if (namei(&nd) == 0) {
 			NDFREE(&nd, NDF_ONLY_PNBUF);
 			error = vn_path_to_global_path(td, nd.ni_vp, pathbuf,
 			    MNAMELEN);
 			if (error == 0 || error == ENODEV)
 				vput(nd.ni_vp);
 		}
 		mtx_lock(&mountlist_mtx);
 		TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
 			if (strcmp(mp->mnt_stat.f_mntonname, pathbuf) == 0) {
 				vfs_ref(mp);
 				break;
 			}
 		}
 		mtx_unlock(&mountlist_mtx);
 	}
 	free(pathbuf, M_TEMP);
 	if (mp == NULL) {
 		/*
 		 * Previously we returned ENOENT for a nonexistent path and
 		 * EINVAL for a non-mountpoint.  We cannot tell these apart
 		 * now, so in the !MNT_BYFSID case return the more likely
 		 * EINVAL for compatibility.
 		 */
 		return ((uap->flags & MNT_BYFSID) ? ENOENT : EINVAL);
 	}
 
 	/*
 	 * Don't allow unmounting the root filesystem.
 	 */
 	if (mp->mnt_flag & MNT_ROOTFS) {
 		vfs_rel(mp);
 		return (EINVAL);
 	}
 	error = dounmount(mp, uap->flags, td);
 	return (error);
 }
 
 /*
  * Return error if any of the vnodes, ignoring the root vnode
  * and the syncer vnode, have non-zero usecount.
  *
  * This function is purely advisory - it can return false positives
  * and negatives.
  */
 static int
 vfs_check_usecounts(struct mount *mp)
 {
 	struct vnode *vp, *mvp;
 
 	MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
 		if ((vp->v_vflag & VV_ROOT) == 0 && vp->v_type != VNON &&
 		    vp->v_usecount != 0) {
 			VI_UNLOCK(vp);
 			MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
 			return (EBUSY);
 		}
 		VI_UNLOCK(vp);
 	}
 
 	return (0);
 }
 
 static void
 dounmount_cleanup(struct mount *mp, struct vnode *coveredvp, int mntkflags)
 {
 
 	mtx_assert(MNT_MTX(mp), MA_OWNED);
 	mp->mnt_kern_flag &= ~mntkflags;
 	if ((mp->mnt_kern_flag & MNTK_MWAIT) != 0) {
 		mp->mnt_kern_flag &= ~MNTK_MWAIT;
 		wakeup(mp);
 	}
 	MNT_IUNLOCK(mp);
 	if (coveredvp != NULL) {
 		VOP_UNLOCK(coveredvp, 0);
 		vdrop(coveredvp);
 	}
 	vn_finished_write(mp);
 }
 
 /*
  * Do the actual filesystem unmount.
  */
 int
 dounmount(struct mount *mp, int flags, struct thread *td)
 {
-	struct vnode *coveredvp, *fsrootvp;
+	struct vnode *coveredvp;
 	int error;
 	uint64_t async_flag;
 	int mnt_gen_r;
 
 	if ((coveredvp = mp->mnt_vnodecovered) != NULL) {
 		mnt_gen_r = mp->mnt_gen;
 		VI_LOCK(coveredvp);
 		vholdl(coveredvp);
 		vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
 		/*
 		 * Check for mp being unmounted while waiting for the
 		 * covered vnode lock.
 		 */
 		if (coveredvp->v_mountedhere != mp ||
 		    coveredvp->v_mountedhere->mnt_gen != mnt_gen_r) {
 			VOP_UNLOCK(coveredvp, 0);
 			vdrop(coveredvp);
 			vfs_rel(mp);
 			return (EBUSY);
 		}
 	}
 
 	/*
 	 * Only privileged root, or (if MNT_USER is set) the user that did the
 	 * original mount is permitted to unmount this filesystem.
 	 */
 	error = vfs_suser(mp, td);
 	if (error != 0) {
 		if (coveredvp != NULL) {
 			VOP_UNLOCK(coveredvp, 0);
 			vdrop(coveredvp);
 		}
 		vfs_rel(mp);
 		return (error);
 	}
 
 	vn_start_write(NULL, &mp, V_WAIT | V_MNTREF);
 	MNT_ILOCK(mp);
 	if ((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0 ||
 	    (mp->mnt_flag & MNT_UPDATE) != 0 ||
 	    !TAILQ_EMPTY(&mp->mnt_uppers)) {
 		dounmount_cleanup(mp, coveredvp, 0);
 		return (EBUSY);
 	}
 	mp->mnt_kern_flag |= MNTK_UNMOUNT | MNTK_NOINSMNTQ;
 	if (flags & MNT_NONBUSY) {
 		MNT_IUNLOCK(mp);
 		error = vfs_check_usecounts(mp);
 		MNT_ILOCK(mp);
 		if (error != 0) {
 			dounmount_cleanup(mp, coveredvp, MNTK_UNMOUNT |
 			    MNTK_NOINSMNTQ);
 			return (error);
 		}
 	}
 	/* Allow filesystems to detect that a forced unmount is in progress. */
 	if (flags & MNT_FORCE) {
 		mp->mnt_kern_flag |= MNTK_UNMOUNTF;
 		MNT_IUNLOCK(mp);
 		/*
 		 * Must be done after setting MNTK_UNMOUNTF and before
 		 * waiting for mnt_lockref to become 0.
 		 */
 		VFS_PURGE(mp);
 		MNT_ILOCK(mp);
 	}
 	error = 0;
 	if (mp->mnt_lockref) {
 		mp->mnt_kern_flag |= MNTK_DRAINING;
 		error = msleep(&mp->mnt_lockref, MNT_MTX(mp), PVFS,
 		    "mount drain", 0);
 	}
 	MNT_IUNLOCK(mp);
 	KASSERT(mp->mnt_lockref == 0,
 	    ("%s: invalid lock refcount in the drain path @ %s:%d",
 	    __func__, __FILE__, __LINE__));
 	KASSERT(error == 0,
 	    ("%s: invalid return value for msleep in the drain path @ %s:%d",
 	    __func__, __FILE__, __LINE__));
 
 	if (mp->mnt_flag & MNT_EXPUBLIC)
 		vfs_setpublicfs(NULL, NULL, NULL);
 
 	/*
 	 * From now, we can claim that the use reference on the
 	 * coveredvp is ours, and the ref can be released only by
 	 * successfull unmount by us, or left for later unmount
 	 * attempt.  The previously acquired hold reference is no
 	 * longer needed to protect the vnode from reuse.
 	 */
 	if (coveredvp != NULL)
 		vdrop(coveredvp);
 
 	vfs_msync(mp, MNT_WAIT);
 	MNT_ILOCK(mp);
 	async_flag = mp->mnt_flag & MNT_ASYNC;
 	mp->mnt_flag &= ~MNT_ASYNC;
 	mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	cache_purgevfs(mp, false); /* remove cache entries for this file sys */
 	vfs_deallocate_syncvnode(mp);
-	/*
-	 * For forced unmounts, move process cdir/rdir refs on the fs root
-	 * vnode to the covered vnode.  For non-forced unmounts we want
-	 * such references to cause an EBUSY error.
-	 */
-	if ((flags & MNT_FORCE) &&
-	    VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
-		if (mp->mnt_vnodecovered != NULL &&
-		    (mp->mnt_flag & MNT_IGNORE) == 0)
-			mountcheckdirs(fsrootvp, mp->mnt_vnodecovered);
-		if (fsrootvp == rootvnode) {
-			vrele(rootvnode);
-			rootvnode = NULL;
-		}
-		vput(fsrootvp);
-	}
 	if ((mp->mnt_flag & MNT_RDONLY) != 0 || (flags & MNT_FORCE) != 0 ||
 	    (error = VFS_SYNC(mp, MNT_WAIT)) == 0)
 		error = VFS_UNMOUNT(mp, flags);
 	vn_finished_write(mp);
 	/*
 	 * If we failed to flush the dirty blocks for this mount point,
 	 * undo all the cdir/rdir and rootvnode changes we made above.
 	 * Unless we failed to do so because the device is reporting that
 	 * it doesn't exist anymore.
 	 */
 	if (error && error != ENXIO) {
-		if ((flags & MNT_FORCE) &&
-		    VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
-			if (mp->mnt_vnodecovered != NULL &&
-			    (mp->mnt_flag & MNT_IGNORE) == 0)
-				mountcheckdirs(mp->mnt_vnodecovered, fsrootvp);
-			if (rootvnode == NULL) {
-				rootvnode = fsrootvp;
-				vref(rootvnode);
-			}
-			vput(fsrootvp);
-		}
 		MNT_ILOCK(mp);
 		mp->mnt_kern_flag &= ~MNTK_NOINSMNTQ;
 		if ((mp->mnt_flag & MNT_RDONLY) == 0) {
 			MNT_IUNLOCK(mp);
 			vfs_allocate_syncvnode(mp);
 			MNT_ILOCK(mp);
 		}
 		mp->mnt_kern_flag &= ~(MNTK_UNMOUNT | MNTK_UNMOUNTF);
 		mp->mnt_flag |= async_flag;
 		if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
 		    (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
 			mp->mnt_kern_flag |= MNTK_ASYNC;
 		if (mp->mnt_kern_flag & MNTK_MWAIT) {
 			mp->mnt_kern_flag &= ~MNTK_MWAIT;
 			wakeup(mp);
 		}
 		MNT_IUNLOCK(mp);
 		if (coveredvp)
 			VOP_UNLOCK(coveredvp, 0);
 		return (error);
 	}
 	mtx_lock(&mountlist_mtx);
 	TAILQ_REMOVE(&mountlist, mp, mnt_list);
 	mtx_unlock(&mountlist_mtx);
 	EVENTHANDLER_INVOKE(vfs_unmounted, mp, td);
 	if (coveredvp != NULL) {
 		coveredvp->v_mountedhere = NULL;
 		VOP_UNLOCK(coveredvp, 0);
 	}
 	vfs_event_signal(NULL, VQ_UNMOUNT, 0);
+	if (rootvnode != NULL && mp == rootvnode->v_mount) {
+		vrele(rootvnode);
+		rootvnode = NULL;
+	}
 	if (mp == rootdevmp)
 		rootdevmp = NULL;
 	vfs_mount_destroy(mp);
 	return (0);
 }
 
 /*
  * Report errors during filesystem mounting.
  */
 void
 vfs_mount_error(struct mount *mp, const char *fmt, ...)
 {
 	struct vfsoptlist *moptlist = mp->mnt_optnew;
 	va_list ap;
 	int error, len;
 	char *errmsg;
 
 	error = vfs_getopt(moptlist, "errmsg", (void **)&errmsg, &len);
 	if (error || errmsg == NULL || len <= 0)
 		return;
 
 	va_start(ap, fmt);
 	vsnprintf(errmsg, (size_t)len, fmt, ap);
 	va_end(ap);
 }
 
 void
 vfs_opterror(struct vfsoptlist *opts, const char *fmt, ...)
 {
 	va_list ap;
 	int error, len;
 	char *errmsg;
 
 	error = vfs_getopt(opts, "errmsg", (void **)&errmsg, &len);
 	if (error || errmsg == NULL || len <= 0)
 		return;
 
 	va_start(ap, fmt);
 	vsnprintf(errmsg, (size_t)len, fmt, ap);
 	va_end(ap);
 }
 
 /*
  * ---------------------------------------------------------------------
  * Functions for querying mount options/arguments from filesystems.
  */
 
 /*
  * Check that no unknown options are given
  */
 int
 vfs_filteropt(struct vfsoptlist *opts, const char **legal)
 {
 	struct vfsopt *opt;
 	char errmsg[255];
 	const char **t, *p, *q;
 	int ret = 0;
 
 	TAILQ_FOREACH(opt, opts, link) {
 		p = opt->name;
 		q = NULL;
 		if (p[0] == 'n' && p[1] == 'o')
 			q = p + 2;
 		for(t = global_opts; *t != NULL; t++) {
 			if (strcmp(*t, p) == 0)
 				break;
 			if (q != NULL) {
 				if (strcmp(*t, q) == 0)
 					break;
 			}
 		}
 		if (*t != NULL)
 			continue;
 		for(t = legal; *t != NULL; t++) {
 			if (strcmp(*t, p) == 0)
 				break;
 			if (q != NULL) {
 				if (strcmp(*t, q) == 0)
 					break;
 			}
 		}
 		if (*t != NULL)
 			continue;
 		snprintf(errmsg, sizeof(errmsg),
 		    "mount option <%s> is unknown", p);
 		ret = EINVAL;
 	}
 	if (ret != 0) {
 		TAILQ_FOREACH(opt, opts, link) {
 			if (strcmp(opt->name, "errmsg") == 0) {
 				strncpy((char *)opt->value, errmsg, opt->len);
 				break;
 			}
 		}
 		if (opt == NULL)
 			printf("%s\n", errmsg);
 	}
 	return (ret);
 }
 
 /*
  * Get a mount option by its name.
  *
  * Return 0 if the option was found, ENOENT otherwise.
  * If len is non-NULL it will be filled with the length
  * of the option. If buf is non-NULL, it will be filled
  * with the address of the option.
  */
 int
 vfs_getopt(struct vfsoptlist *opts, const char *name, void **buf, int *len)
 {
 	struct vfsopt *opt;
 
 	KASSERT(opts != NULL, ("vfs_getopt: caller passed 'opts' as NULL"));
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) == 0) {
 			opt->seen = 1;
 			if (len != NULL)
 				*len = opt->len;
 			if (buf != NULL)
 				*buf = opt->value;
 			return (0);
 		}
 	}
 	return (ENOENT);
 }
 
 int
 vfs_getopt_pos(struct vfsoptlist *opts, const char *name)
 {
 	struct vfsopt *opt;
 
 	if (opts == NULL)
 		return (-1);
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) == 0) {
 			opt->seen = 1;
 			return (opt->pos);
 		}
 	}
 	return (-1);
 }
 
 int
 vfs_getopt_size(struct vfsoptlist *opts, const char *name, off_t *value)
 {
 	char *opt_value, *vtp;
 	quad_t iv;
 	int error, opt_len;
 
 	error = vfs_getopt(opts, name, (void **)&opt_value, &opt_len);
 	if (error != 0)
 		return (error);
 	if (opt_len == 0 || opt_value == NULL)
 		return (EINVAL);
 	if (opt_value[0] == '\0' || opt_value[opt_len - 1] != '\0')
 		return (EINVAL);
 	iv = strtoq(opt_value, &vtp, 0);
 	if (vtp == opt_value || (vtp[0] != '\0' && vtp[1] != '\0'))
 		return (EINVAL);
 	if (iv < 0)
 		return (EINVAL);
 	switch (vtp[0]) {
 	case 't':
 	case 'T':
 		iv *= 1024;
 	case 'g':
 	case 'G':
 		iv *= 1024;
 	case 'm':
 	case 'M':
 		iv *= 1024;
 	case 'k':
 	case 'K':
 		iv *= 1024;
 	case '\0':
 		break;
 	default:
 		return (EINVAL);
 	}
 	*value = iv;
 
 	return (0);
 }
 
 char *
 vfs_getopts(struct vfsoptlist *opts, const char *name, int *error)
 {
 	struct vfsopt *opt;
 
 	*error = 0;
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) != 0)
 			continue;
 		opt->seen = 1;
 		if (opt->len == 0 ||
 		    ((char *)opt->value)[opt->len - 1] != '\0') {
 			*error = EINVAL;
 			return (NULL);
 		}
 		return (opt->value);
 	}
 	*error = ENOENT;
 	return (NULL);
 }
 
 int
 vfs_flagopt(struct vfsoptlist *opts, const char *name, uint64_t *w,
 	uint64_t val)
 {
 	struct vfsopt *opt;
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) == 0) {
 			opt->seen = 1;
 			if (w != NULL)
 				*w |= val;
 			return (1);
 		}
 	}
 	if (w != NULL)
 		*w &= ~val;
 	return (0);
 }
 
 int
 vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt, ...)
 {
 	va_list ap;
 	struct vfsopt *opt;
 	int ret;
 
 	KASSERT(opts != NULL, ("vfs_getopt: caller passed 'opts' as NULL"));
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) != 0)
 			continue;
 		opt->seen = 1;
 		if (opt->len == 0 || opt->value == NULL)
 			return (0);
 		if (((char *)opt->value)[opt->len - 1] != '\0')
 			return (0);
 		va_start(ap, fmt);
 		ret = vsscanf(opt->value, fmt, ap);
 		va_end(ap);
 		return (ret);
 	}
 	return (0);
 }
 
 int
 vfs_setopt(struct vfsoptlist *opts, const char *name, void *value, int len)
 {
 	struct vfsopt *opt;
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) != 0)
 			continue;
 		opt->seen = 1;
 		if (opt->value == NULL)
 			opt->len = len;
 		else {
 			if (opt->len != len)
 				return (EINVAL);
 			bcopy(value, opt->value, len);
 		}
 		return (0);
 	}
 	return (ENOENT);
 }
 
 int
 vfs_setopt_part(struct vfsoptlist *opts, const char *name, void *value, int len)
 {
 	struct vfsopt *opt;
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) != 0)
 			continue;
 		opt->seen = 1;
 		if (opt->value == NULL)
 			opt->len = len;
 		else {
 			if (opt->len < len)
 				return (EINVAL);
 			opt->len = len;
 			bcopy(value, opt->value, len);
 		}
 		return (0);
 	}
 	return (ENOENT);
 }
 
 int
 vfs_setopts(struct vfsoptlist *opts, const char *name, const char *value)
 {
 	struct vfsopt *opt;
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) != 0)
 			continue;
 		opt->seen = 1;
 		if (opt->value == NULL)
 			opt->len = strlen(value) + 1;
 		else if (strlcpy(opt->value, value, opt->len) >= opt->len)
 			return (EINVAL);
 		return (0);
 	}
 	return (ENOENT);
 }
 
 /*
  * Find and copy a mount option.
  *
  * The size of the buffer has to be specified
  * in len, if it is not the same length as the
  * mount option, EINVAL is returned.
  * Returns ENOENT if the option is not found.
  */
 int
 vfs_copyopt(struct vfsoptlist *opts, const char *name, void *dest, int len)
 {
 	struct vfsopt *opt;
 
 	KASSERT(opts != NULL, ("vfs_copyopt: caller passed 'opts' as NULL"));
 
 	TAILQ_FOREACH(opt, opts, link) {
 		if (strcmp(name, opt->name) == 0) {
 			opt->seen = 1;
 			if (len != opt->len)
 				return (EINVAL);
 			bcopy(opt->value, dest, opt->len);
 			return (0);
 		}
 	}
 	return (ENOENT);
 }
 
 int
 __vfs_statfs(struct mount *mp, struct statfs *sbp)
 {
 	int error;
 
 	error = mp->mnt_op->vfs_statfs(mp, &mp->mnt_stat);
 	if (sbp != &mp->mnt_stat)
 		*sbp = mp->mnt_stat;
 	return (error);
 }
 
 void
 vfs_mountedfrom(struct mount *mp, const char *from)
 {
 
 	bzero(mp->mnt_stat.f_mntfromname, sizeof mp->mnt_stat.f_mntfromname);
 	strlcpy(mp->mnt_stat.f_mntfromname, from,
 	    sizeof mp->mnt_stat.f_mntfromname);
 }
 
 /*
  * ---------------------------------------------------------------------
  * This is the api for building mount args and mounting filesystems from
  * inside the kernel.
  *
  * The API works by accumulation of individual args.  First error is
  * latched.
  *
  * XXX: should be documented in new manpage kernel_mount(9)
  */
 
 /* A memory allocation which must be freed when we are done */
 struct mntaarg {
 	SLIST_ENTRY(mntaarg)	next;
 };
 
 /* The header for the mount arguments */
 struct mntarg {
 	struct iovec *v;
 	int len;
 	int error;
 	SLIST_HEAD(, mntaarg)	list;
 };
 
 /*
  * Add a boolean argument.
  *
  * flag is the boolean value.
  * name must start with "no".
  */
 struct mntarg *
 mount_argb(struct mntarg *ma, int flag, const char *name)
 {
 
 	KASSERT(name[0] == 'n' && name[1] == 'o',
 	    ("mount_argb(...,%s): name must start with 'no'", name));
 
 	return (mount_arg(ma, name + (flag ? 2 : 0), NULL, 0));
 }
 
 /*
  * Add an argument printf style
  */
 struct mntarg *
 mount_argf(struct mntarg *ma, const char *name, const char *fmt, ...)
 {
 	va_list ap;
 	struct mntaarg *maa;
 	struct sbuf *sb;
 	int len;
 
 	if (ma == NULL) {
 		ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
 		SLIST_INIT(&ma->list);
 	}
 	if (ma->error)
 		return (ma);
 
 	ma->v = realloc(ma->v, sizeof *ma->v * (ma->len + 2),
 	    M_MOUNT, M_WAITOK);
 	ma->v[ma->len].iov_base = (void *)(uintptr_t)name;
 	ma->v[ma->len].iov_len = strlen(name) + 1;
 	ma->len++;
 
 	sb = sbuf_new_auto();
 	va_start(ap, fmt);
 	sbuf_vprintf(sb, fmt, ap);
 	va_end(ap);
 	sbuf_finish(sb);
 	len = sbuf_len(sb) + 1;
 	maa = malloc(sizeof *maa + len, M_MOUNT, M_WAITOK | M_ZERO);
 	SLIST_INSERT_HEAD(&ma->list, maa, next);
 	bcopy(sbuf_data(sb), maa + 1, len);
 	sbuf_delete(sb);
 
 	ma->v[ma->len].iov_base = maa + 1;
 	ma->v[ma->len].iov_len = len;
 	ma->len++;
 
 	return (ma);
 }
 
 /*
  * Add an argument which is a userland string.
  */
 struct mntarg *
 mount_argsu(struct mntarg *ma, const char *name, const void *val, int len)
 {
 	struct mntaarg *maa;
 	char *tbuf;
 
 	if (val == NULL)
 		return (ma);
 	if (ma == NULL) {
 		ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
 		SLIST_INIT(&ma->list);
 	}
 	if (ma->error)
 		return (ma);
 	maa = malloc(sizeof *maa + len, M_MOUNT, M_WAITOK | M_ZERO);
 	SLIST_INSERT_HEAD(&ma->list, maa, next);
 	tbuf = (void *)(maa + 1);
 	ma->error = copyinstr(val, tbuf, len, NULL);
 	return (mount_arg(ma, name, tbuf, -1));
 }
 
 /*
  * Plain argument.
  *
  * If length is -1, treat value as a C string.
  */
 struct mntarg *
 mount_arg(struct mntarg *ma, const char *name, const void *val, int len)
 {
 
 	if (ma == NULL) {
 		ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
 		SLIST_INIT(&ma->list);
 	}
 	if (ma->error)
 		return (ma);
 
 	ma->v = realloc(ma->v, sizeof *ma->v * (ma->len + 2),
 	    M_MOUNT, M_WAITOK);
 	ma->v[ma->len].iov_base = (void *)(uintptr_t)name;
 	ma->v[ma->len].iov_len = strlen(name) + 1;
 	ma->len++;
 
 	ma->v[ma->len].iov_base = (void *)(uintptr_t)val;
 	if (len < 0)
 		ma->v[ma->len].iov_len = strlen(val) + 1;
 	else
 		ma->v[ma->len].iov_len = len;
 	ma->len++;
 	return (ma);
 }
 
 /*
  * Free a mntarg structure
  */
 static void
 free_mntarg(struct mntarg *ma)
 {
 	struct mntaarg *maa;
 
 	while (!SLIST_EMPTY(&ma->list)) {
 		maa = SLIST_FIRST(&ma->list);
 		SLIST_REMOVE_HEAD(&ma->list, next);
 		free(maa, M_MOUNT);
 	}
 	free(ma->v, M_MOUNT);
 	free(ma, M_MOUNT);
 }
 
 /*
  * Mount a filesystem
  */
 int
 kernel_mount(struct mntarg *ma, uint64_t flags)
 {
 	struct uio auio;
 	int error;
 
 	KASSERT(ma != NULL, ("kernel_mount NULL ma"));
 	KASSERT(ma->v != NULL, ("kernel_mount NULL ma->v"));
 	KASSERT(!(ma->len & 1), ("kernel_mount odd ma->len (%d)", ma->len));
 
 	auio.uio_iov = ma->v;
 	auio.uio_iovcnt = ma->len;
 	auio.uio_segflg = UIO_SYSSPACE;
 
 	error = ma->error;
 	if (!error)
 		error = vfs_donmount(curthread, flags, &auio);
 	free_mntarg(ma);
 	return (error);
 }
 
 /*
  * A printflike function to mount a filesystem.
  */
 int
 kernel_vmount(int flags, ...)
 {
 	struct mntarg *ma = NULL;
 	va_list ap;
 	const char *cp;
 	const void *vp;
 	int error;
 
 	va_start(ap, flags);
 	for (;;) {
 		cp = va_arg(ap, const char *);
 		if (cp == NULL)
 			break;
 		vp = va_arg(ap, const void *);
 		ma = mount_arg(ma, cp, vp, (vp != NULL ? -1 : 0));
 	}
 	va_end(ap);
 
 	error = kernel_mount(ma, flags);
 	return (error);
 }
 
 void
 vfs_oexport_conv(const struct oexport_args *oexp, struct export_args *exp)
 {
 
 	bcopy(oexp, exp, sizeof(*oexp));
 	exp->ex_numsecflavors = 0;
 }