--- usr.sbin/mountd/mountd.c
+++ usr.sbin/mountd/mountd.c
@@ -2047,6 +2047,8 @@
 		} else if (!strcmp(cpopt, "webnfs")) {
 			*exflagsp |= (MNT_EXPUBLIC|MNT_EXRDONLY|MNT_EXPORTANON);
 			opt_flags |= OP_MAPALL;
+		} else if (!strcmp(cpopt, "recursive")) {
+			*exflagsp |= MNT_EXRECURSIVE;
 		} else if (cpoptarg && !strcmp(cpopt, "index")) {
 			ep->ex_indexfile = strdup(cpoptarg);
 		} else if (!strcmp(cpopt, "quiet")) {
--- cddl/compat/opensolaris/misc/fsshare.c
+++ cddl/compat/opensolaris/misc/fsshare.c
@@ -112,11 +112,12 @@
  *
  * Recognized keywords:
  *
- *	ro, maproot, mapall, mask, network, alldirs, public, webnfs, index, quiet
+ *	ro, maproot, mapall, mask, network, alldirs, recursive, public, webnfs, index, quiet
  *
  */
 static const char *known_opts[] = { "ro", "maproot", "mapall", "mask",
-    "network", "alldirs", "public", "webnfs", "index", "quiet", NULL };
+    "network", "alldirs", "recursive", "public", "webnfs", "index", "quiet",
+    NULL };
 static char *
 translate_opts(const char *shareopts)
 {
--- sys/sys/mount.h
+++ sys/sys/mount.h
@@ -250,6 +250,8 @@
 #define	MNT_EXPORTANON	0x00000400	/* use anon uid mapping for everyone */
 #define	MNT_EXKERB	0x00000800	/* exported with Kerberos uid mapping */
 #define	MNT_EXPUBLIC	0x20000000	/* public export (WebNFS) */
+#define	MNT_EXRECURSIVE	0x00000001	/* entire file systems hierarchy is
+					   recursively exported */
 
 /*
  * Flags set by internal operations,
@@ -750,6 +752,8 @@
 extern	TAILQ_HEAD(mntlist, mount) mountlist;	/* mounted filesystem list */
 extern	struct mtx mountlist_mtx;
 extern	struct nfs_public nfs_pub;
+struct mount *vfs_exrecursive(struct mount *, struct sockaddr *);
+int	vfs_extraverse(struct vnode **, struct sockaddr *);
 
 /*
  * Declarations for these vfs default operations are located in
--- sys/kern/vfs_export.c
+++ sys/kern/vfs_export.c
@@ -457,6 +457,71 @@
 	return (np);
 }
 
+struct mount *
+vfs_exrecursive(struct mount *mp, struct sockaddr *nam)
+{
+	struct netcred *np;
+	struct mount *pmp;
+
+	pmp = mp;
+	for (;;) {
+		lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
+		if (mp->mnt_export == NULL)
+			break;
+		np = vfs_export_lookup(mp, nam);
+		if (np == NULL)
+			break;
+		if (!(np->netc_exflags & MNT_EXRECURSIVE))
+			break;
+		lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
+		if (mp->mnt_vnodecovered == NULL)
+			return (mp);
+		pmp = mp;
+		mp = pmp->mnt_vnodecovered->v_mount;
+	}
+	lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
+	if (mp != pmp)
+		return (pmp);
+	return (NULL);
+}
+
+int
+vfs_extraverse(struct vnode **cvpp, struct sockaddr *nam)
+{
+	struct vnode *cvp, *tvp;
+	struct mount *mp;
+	struct netcred *np;
+	int error, lktype;
+
+	cvp = *cvpp;
+	if (cvp->v_type != VDIR)
+		return (0);
+	lktype = VOP_ISLOCKED(cvp);
+	for (;;) {
+		mp = cvp->v_mountedhere;
+		if (mp == NULL)
+			goto nounlock;
+		lockmgr(&mp->mnt_explock, LK_SHARED, NULL);
+		if (mp->mnt_export == NULL)
+			break;
+		np = vfs_export_lookup(mp, nam);
+		if (np == NULL)
+			break;
+		if (!(np->netc_exflags & MNT_EXRECURSIVE))
+			break;
+		lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
+		vput(cvp);
+		error = VFS_ROOT(mp, lktype, &tvp);
+		if (error != 0)
+			return (error);
+		cvp = tvp;
+	}
+	lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
+nounlock:
+	*cvpp = cvp;
+	return (0);
+}
+
 /*
  * XXX: This comment comes from the deprecated ufs_check_export()
  * XXX: and may not entirely apply, but lacking something better:
--- sys/kern/vfs_lookup.c
+++ sys/kern/vfs_lookup.c
@@ -625,9 +625,7 @@
 			if (dp == ndp->ni_rootdir || 
 			    dp == ndp->ni_topdir || 
 			    dp == rootvnode ||
-			    pr != NULL ||
-			    ((dp->v_vflag & VV_ROOT) != 0 &&
-			     (cnp->cn_flags & NOCROSSMOUNT) != 0)) {
+			    pr != NULL) {
 				ndp->ni_dvp = dp;
 				ndp->ni_vp = dp;
 				vfslocked = VFS_LOCK_GIANT(dp->v_mount);
--- sys/nfsclient/nfs_subs.c
+++ sys/nfsclient/nfs_subs.c
@@ -545,8 +545,8 @@
 	vap->va_rdev = rdev;
 	mtime_save = vap->va_mtime;
 	vap->va_mtime = mtime;
-	vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
 	if (v3) {
+		vap->va_fsid = fxdr_hyper(&fp->fa3_fsid);
 		vap->va_nlink = fxdr_unsigned(u_short, fp->fa_nlink);
 		vap->va_uid = fxdr_unsigned(uid_t, fp->fa_uid);
 		vap->va_gid = fxdr_unsigned(gid_t, fp->fa_gid);
@@ -560,6 +560,7 @@
 		vap->va_flags = 0;
 		vap->va_filerev = 0;
 	} else {
+		vap->va_fsid = fxdr_unsigned(u_int32_t, fp->fa2_fsid);
 		vap->va_nlink = fxdr_unsigned(u_short, fp->fa_nlink);
 		vap->va_uid = fxdr_unsigned(uid_t, fp->fa_uid);
 		vap->va_gid = fxdr_unsigned(gid_t, fp->fa_gid);
--- sys/nfsserver/nfs_serv.c
+++ sys/nfsserver/nfs_serv.c
@@ -607,9 +607,12 @@
 	 * the same potential blocking reason ) and reply.
 	 */
 	vp = ndp->ni_vp;
-	bzero((caddr_t)fhp, sizeof(nfh));
-	fhp->fh_fsid = vp->v_mount->mnt_stat.f_fsid;
-	error = VOP_VPTOFH(vp, &fhp->fh_fid);
+	error = vfs_extraverse(&vp, nam);
+	if (!error) {
+		bzero((caddr_t)fhp, sizeof(nfh));
+		fhp->fh_fsid = vp->v_mount->mnt_stat.f_fsid;
+		error = VOP_VPTOFH(vp, &fhp->fh_fid);
+	}
 	if (!error)
 		error = VOP_GETATTR(vp, vap, cred);
 
@@ -3231,16 +3234,14 @@
 			if (VFS_VGET(vp->v_mount, dp->d_fileno, LK_EXCLUSIVE,
 			    &nvp))
 				goto invalid;
+			if (vfs_extraverse(&nvp, nam)) {
+				vput(nvp);
+				nvp = NULL;
+				goto invalid;
+			}
 			bzero((caddr_t)nfhp, NFSX_V3FH);
 			nfhp->fh_fsid =
 				nvp->v_mount->mnt_stat.f_fsid;
-			/*
-			 * XXXRW: Assert the mountpoints are the same so that
-			 * we know that acquiring Giant based on the
-			 * directory is the right thing for the child.
-			 */
-			KASSERT(nvp->v_mount == vp->v_mount,
-			    ("nfsrv_readdirplus: nvp mount != vp mount"));
 			if (VOP_VPTOFH(nvp, &nfhp->fh_fid)) {
 				vput(nvp);
 				nvp = NULL;
--- sys/nfsserver/nfs_srvsubs.c
+++ sys/nfsserver/nfs_srvsubs.c
@@ -590,7 +590,7 @@
 	char *fromcp, *tocp, *cp;
 	struct iovec aiov;
 	struct uio auio;
-	struct vnode *dp;
+	struct vnode *dp, *topvp;
 	int error, rdonly, linklen;
 	struct componentname *cnp = &ndp->ni_cnd;
 	int lockleaf = (cnp->cn_flags & LOCKLEAF) != 0;
@@ -600,6 +600,7 @@
 	vfslocked = 0;
 	dvfslocked = 0;
 	*retdirp = NULL;
+	topvp = NULL;
 	cnp->cn_flags |= NOMACCHECK;
 	cnp->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
 
@@ -733,6 +734,20 @@
 			vfslocked = tvfslocked;
 		}
 	} else {
+		struct mount *mp;
+
+		/*
+		 * For recursive export limit lookup to the root of
+		 * the exported hierarchy.
+		 */
+		mp = vfs_exrecursive(dp->v_mount, nam);
+		if (mp == NULL)
+			mp = dp->v_mount;
+		error = VFS_ROOT(mp, LK_SHARED, &topvp);
+		KASSERT(error == 0, ("VFS_ROOT(%s) failed (error=%d).",
+		    mp->mnt_stat.f_mntonname, error));
+		VOP_UNLOCK(topvp, 0);
+		ndp->ni_topdir = topvp;
 		cnp->cn_flags |= NOCROSSMOUNT;
 	}
 
@@ -862,6 +877,8 @@
 		mtx_unlock(&Giant);
 		cnp->cn_flags &= ~GIANTHELD;
 	}
+	if (topvp != NULL)
+		vrele(topvp);
 
 	/*
 	 * nfs_namei() guarentees that fields will not contain garbage
--- sys/fs/nfsserver/nfs_nfsdport.c
+++ sys/fs/nfsserver/nfs_nfsdport.c
@@ -241,6 +241,7 @@
     struct vnode **retdirp)
 {
 	struct componentname *cnp = &ndp->ni_cnd;
+	struct vnode *topvp;
 	int i;
 	struct iovec aiov;
 	struct uio auio;
@@ -248,6 +249,7 @@
 	int error = 0, crossmnt;
 	char *cp;
 
+	topvp = NULL;
 	*retdirp = NULL;
 	cnp->cn_nameptr = cnp->cn_pnbuf;
 	/*
@@ -295,6 +297,11 @@
 		 * mount while traversing the file system above
 		 * the mount point, unless enable_crossmntpt is set.
 		 */
+		error = VFS_ROOT(dp->v_mount, LK_SHARED, &topvp);
+		KASSERT(error == 0, ("VFS_ROOT(%s) failed (error=%d).",
+		    dp->v_mount->mnt_stat.f_mntonname, error));
+		VOP_UNLOCK(topvp, 0);
+		ndp->ni_topdir = topvp;
 		cnp->cn_flags |= NOCROSSMOUNT;
 		crossmnt = 0;
 	}
@@ -426,6 +433,8 @@
 		cnp->cn_flags &= ~LOCKLEAF;
 
 out:
+	if (topvp != NULL)
+		vrele(topvp);
 	if (error) {
 		uma_zfree(namei_zone, cnp->cn_pnbuf);
 		ndp->ni_vp = NULL;