Index: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_vfsops.h
===================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_vfsops.h
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_vfsops.h
@@ -46,6 +46,8 @@
 	zfsvfs_t	*z_parent;	/* parent fs */
 	objset_t	*z_os;		/* objset reference */
 	uint64_t	z_root;		/* id of root znode */
+	struct vnode	*z_rootvnode;	/* root vnode */
+	struct rmlock	z_rootvnodelock;/* protection for root vnode */
 	uint64_t	z_unlinkedobj;	/* id of unlinked zapobj */
 	uint64_t	z_max_blksz;	/* maximum block size for files */
 	uint64_t	z_fuid_obj;	/* fuid table object number */
Index: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
===================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
@@ -65,6 +65,7 @@
 #include <sys/spa_boot.h>
 #include <sys/jail.h>
 #include <ufs/ufs/quota.h>
+#include <sys/rmlock.h>
 
 #include "zfs_comutil.h"
 
@@ -92,6 +93,9 @@
 SYSCTL_INT(_vfs_zfs_version, OID_AUTO, zpl, CTLFLAG_RD, &zfs_version_zpl, 0,
     "ZPL_VERSION");
 
+static int zfs_root_setvnode(zfsvfs_t *zfsvfs);
+static void zfs_root_dropvnode(zfsvfs_t *zfsvfs);
+
 static int zfs_quotactl(vfs_t *vfsp, int cmds, uid_t id, void *arg);
 static int zfs_mount(vfs_t *vfsp);
 static int zfs_umount(vfs_t *vfsp, int fflag);
@@ -1209,6 +1213,8 @@
 	for (int i = 0; i != ZFS_OBJ_MTX_SZ; i++)
 		mutex_init(&zfsvfs->z_hold_mtx[i], NULL, MUTEX_DEFAULT, NULL);
 
+	rm_init(&zfsvfs->z_rootvnodelock, "zfs root vnode lock");
+
 	error = zfsvfs_init(zfsvfs, os);
 	if (error != 0) {
 		*zfvp = NULL;
@@ -1315,6 +1321,8 @@
 	rw_enter(&zfsvfs_lock, RW_READER);
 	rw_exit(&zfsvfs_lock);
 
+	rm_destroy(&zfsvfs->z_rootvnodelock);
+
 	zfs_fuid_destroy(zfsvfs);
 
 	mutex_destroy(&zfsvfs->z_znodes_lock);
@@ -1921,6 +1929,8 @@
 	error = zfs_domount(vfsp, osname);
 	PICKUP_GIANT();
 
+	zfs_root_setvnode((zfsvfs_t *)vfsp->vfs_data);
+
 #ifdef illumos
 	/*
 	 * Add an extra VFS_HOLD on our parent vfs so that it can't
@@ -1993,14 +2003,65 @@
 }
 
 static int
+zfs_root_setvnode(zfsvfs_t *zfsvfs)
+{
+	znode_t *rootzp;
+	int error;
+
+	ZFS_ENTER(zfsvfs);
+	error = zfs_zget(zfsvfs, zfsvfs->z_root, &rootzp);
+	if (error != 0)
+		panic("could not zfs_zget for root vnode");
+	ZFS_EXIT(zfsvfs);
+
+	rm_wlock(&zfsvfs->z_rootvnodelock);
+	if (zfsvfs->z_rootvnode != NULL)
+		panic("zfs mount point already has a root vnode: %p\n",
+		    zfsvfs->z_rootvnode);
+	zfsvfs->z_rootvnode = ZTOV(rootzp);
+	rm_wunlock(&zfsvfs->z_rootvnodelock);
+	return (0);
+}
+
+static void
+zfs_root_putvnode(zfsvfs_t *zfsvfs)
+{
+	struct vnode *vp;
+
+	rm_wlock(&zfsvfs->z_rootvnodelock);
+	vp = zfsvfs->z_rootvnode;
+	zfsvfs->z_rootvnode = NULL;
+	rm_wunlock(&zfsvfs->z_rootvnodelock);
+	if (vp != NULL)
+		vrele(vp);
+}
+
+static int
 zfs_root(vfs_t *vfsp, int flags, vnode_t **vpp)
 {
+	struct rm_priotracker tracker;
 	zfsvfs_t *zfsvfs = vfsp->vfs_data;
 	znode_t *rootzp;
 	int error;
 
-	ZFS_ENTER(zfsvfs);
+	rm_rlock(&zfsvfs->z_rootvnodelock, &tracker);
+	*vpp = zfsvfs->z_rootvnode;
+	if (*vpp != NULL && (((*vpp)->v_iflag & VI_DOOMED) == 0)) {
+		vrefact(*vpp);
+		rm_runlock(&zfsvfs->z_rootvnodelock, &tracker);
+		goto lock;
+	}
+	rm_runlock(&zfsvfs->z_rootvnodelock, &tracker);
 
+	/*
+	 * We found the vnode but did not like it.
+	 */
+	if (*vpp != NULL) {
+		*vpp = NULL;
+		zfs_root_putvnode(zfsvfs);
+	}
+
+	ZFS_ENTER(zfsvfs);
 	error = zfs_zget(zfsvfs, zfsvfs->z_root, &rootzp);
 	if (error == 0)
 		*vpp = ZTOV(rootzp);
@@ -2008,6 +2069,7 @@
 	ZFS_EXIT(zfsvfs);
 
 	if (error == 0) {
+lock:
 		error = vn_lock(*vpp, flags);
 		if (error != 0) {
 			VN_RELE(*vpp);
@@ -2125,6 +2187,8 @@
 	objset_t *os;
 	cred_t *cr = td->td_ucred;
 	int ret;
+
+	zfs_root_putvnode(zfsvfs);
 
 	ret = secpolicy_fs_unmount(cr, vfsp);
 	if (ret) {