Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c
@@ -826,6 +826,7 @@
 	.vop_pathconf =	zfsctl_common_pathconf,
 	.vop_getacl =	zfsctl_common_getacl,
 };
+VFS_VOP_VECTOR_REGISTER(zfsctl_ops_root);
 
 static int
 zfsctl_snapshot_zname(vnode_t *vp, const char *name, int len, char *zname)
@@ -1159,6 +1160,7 @@
 	.vop_pathconf =	zfsctl_common_pathconf,
 	.vop_getacl =	zfsctl_common_getacl,
 };
+VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapdir);
 
 static int
 zfsctl_snapshot_inactive(ap)
@@ -1257,6 +1259,7 @@
 	.vop_advlockpurge =	vop_stdadvlockpurge, /* called by vgone */
 	.vop_print =		zfsctl_common_print,
 };
+VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapshot);
 
 int
 zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
@@ -5995,6 +5995,7 @@
 	.vop_unlock =		vop_unlock,
 	.vop_islocked =		vop_islocked,
 };
+VFS_VOP_VECTOR_REGISTER(zfs_vnodeops);
 
 struct vop_vector zfs_fifoops = {
 	.vop_default =		&fifo_specops,
@@ -6012,6 +6013,7 @@
 	.vop_setacl =		zfs_freebsd_setacl,
 	.vop_aclcheck =		zfs_freebsd_aclcheck,
 };
+VFS_VOP_VECTOR_REGISTER(zfs_fifoops);
 
 /*
  * special share hidden files vnode operations template
@@ -6024,3 +6026,4 @@
 	.vop_fid =		zfs_freebsd_fid,
 	.vop_pathconf =		zfs_freebsd_pathconf,
 };
+VFS_VOP_VECTOR_REGISTER(zfs_shareops);
Index: sys/fs/autofs/autofs_vnops.c
===================================================================
--- sys/fs/autofs/autofs_vnops.c
+++ sys/fs/autofs/autofs_vnops.c
@@ -554,6 +554,7 @@
 	.vop_write =		VOP_EOPNOTSUPP,
 	.vop_reclaim =		autofs_reclaim,
 };
+VFS_VOP_VECTOR_REGISTER(autofs_vnodeops);
 
 int
 autofs_node_new(struct autofs_node *parent, struct autofs_mount *amp,
Index: sys/fs/cd9660/cd9660_vnops.c
===================================================================
--- sys/fs/cd9660/cd9660_vnops.c
+++ sys/fs/cd9660/cd9660_vnops.c
@@ -906,6 +906,7 @@
 	.vop_vptofh =		cd9660_vptofh,
 	.vop_getpages =		cd9660_getpages,
 };
+VFS_VOP_VECTOR_REGISTER(cd9660_vnodeops);
 
 /*
  * Special device vnode ops
@@ -920,3 +921,4 @@
 	.vop_setattr =		cd9660_setattr,
 	.vop_vptofh =		cd9660_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(cd9660_fifoops);
Index: sys/fs/deadfs/dead_vnops.c
===================================================================
--- sys/fs/deadfs/dead_vnops.c
+++ sys/fs/deadfs/dead_vnops.c
@@ -80,6 +80,7 @@
 	.vop_unset_text =	dead_unset_text,
 	.vop_write =		dead_write,
 };
+VFS_VOP_VECTOR_REGISTER(dead_vnodeops);
 
 static int
 dead_getwritemount(struct vop_getwritemount_args *ap)
Index: sys/fs/devfs/devfs_vnops.c
===================================================================
--- sys/fs/devfs/devfs_vnops.c
+++ sys/fs/devfs/devfs_vnops.c
@@ -1928,6 +1928,7 @@
 	.vop_symlink =		devfs_symlink,
 	.vop_vptocnp =		devfs_vptocnp,
 };
+VFS_VOP_VECTOR_REGISTER(devfs_vnodeops);
 
 /* Vops for VCHR vnodes in /dev. */
 static struct vop_vector devfs_specops = {
@@ -1965,6 +1966,7 @@
 	.vop_vptocnp =		devfs_vptocnp,
 	.vop_write =		dead_write,
 };
+VFS_VOP_VECTOR_REGISTER(devfs_specops);
 
 /*
  * Our calling convention to the device drivers used to be that we passed
Index: sys/fs/ext2fs/ext2_vnops.c
===================================================================
--- sys/fs/ext2fs/ext2_vnops.c
+++ sys/fs/ext2fs/ext2_vnops.c
@@ -182,6 +182,7 @@
 #endif /* UFS_ACL */
 	.vop_vptofh =		ext2_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ext2_vnodeops);
 
 struct vop_vector ext2_fifoops = {
 	.vop_default =		&fifo_specops,
@@ -199,6 +200,7 @@
 	.vop_write =		VOP_PANIC,
 	.vop_vptofh =		ext2_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ext2_fifoops);
 
 /*
  * A virgin directory (no blushing please).
Index: sys/fs/fdescfs/fdesc_vnops.c
===================================================================
--- sys/fs/fdescfs/fdesc_vnops.c
+++ sys/fs/fdescfs/fdesc_vnops.c
@@ -91,6 +91,7 @@
 	.vop_reclaim =		fdesc_reclaim,
 	.vop_setattr =		fdesc_setattr,
 };
+VFS_VOP_VECTOR_REGISTER(fdesc_vnodeops);
 
 static void fdesc_insmntque_dtr(struct vnode *, void *);
 static void fdesc_remove_entry(struct fdescnode *);
Index: sys/fs/fifofs/fifo_vnops.c
===================================================================
--- sys/fs/fifofs/fifo_vnops.c
+++ sys/fs/fifofs/fifo_vnops.c
@@ -102,6 +102,7 @@
 	.vop_symlink =		VOP_PANIC,
 	.vop_write =		VOP_PANIC,
 };
+VFS_VOP_VECTOR_REGISTER(fifo_specops);
 
 /*
  * Dispose of fifo resources.
Index: sys/fs/fuse/fuse_vnops.c
===================================================================
--- sys/fs/fuse/fuse_vnops.c
+++ sys/fs/fuse/fuse_vnops.c
@@ -174,6 +174,7 @@
 	.vop_write =		VOP_PANIC,
 	.vop_vptofh =		fuse_vnop_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(fuse_fifoops);
 
 struct vop_vector fuse_vnops = {
 	.vop_allocate =	VOP_EINVAL,
@@ -223,6 +224,7 @@
 	.vop_print = fuse_vnop_print,
 	.vop_vptofh = fuse_vnop_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(fuse_vnops);
 
 uma_zone_t fuse_pbuf_zone;
 
Index: sys/fs/msdosfs/msdosfs_vnops.c
===================================================================
--- sys/fs/msdosfs/msdosfs_vnops.c
+++ sys/fs/msdosfs/msdosfs_vnops.c
@@ -1962,3 +1962,4 @@
 	.vop_write =		msdosfs_write,
 	.vop_vptofh =		msdosfs_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(msdosfs_vnodeops);
Index: sys/fs/nfsclient/nfs_clvnops.c
===================================================================
--- sys/fs/nfsclient/nfs_clvnops.c
+++ sys/fs/nfsclient/nfs_clvnops.c
@@ -182,6 +182,7 @@
 	.vop_getacl =		nfs_getacl,
 	.vop_setacl =		nfs_setacl,
 };
+VFS_VOP_VECTOR_REGISTER(newnfs_vnodeops_nosig);
 
 static int
 nfs_vnodeops_bypass(struct vop_generic_args *a)
@@ -194,6 +195,7 @@
 	.vop_default =		&default_vnodeops,
 	.vop_bypass =		nfs_vnodeops_bypass,
 };
+VFS_VOP_VECTOR_REGISTER(newnfs_vnodeops);
 
 static struct vop_vector newnfs_fifoops_nosig = {
 	.vop_default =		&fifo_specops,
@@ -209,6 +211,7 @@
 	.vop_setattr =		nfs_setattr,
 	.vop_write =		nfsfifo_write,
 };
+VFS_VOP_VECTOR_REGISTER(newnfs_fifoops_nosig);
 
 static int
 nfs_fifoops_bypass(struct vop_generic_args *a)
@@ -221,6 +224,7 @@
 	.vop_default =		&default_vnodeops,
 	.vop_bypass =		nfs_fifoops_bypass,
 };
+VFS_VOP_VECTOR_REGISTER(newnfs_fifoops);
 
 static int nfs_mknodrpc(struct vnode *dvp, struct vnode **vpp,
     struct componentname *cnp, struct vattr *vap);
Index: sys/fs/nullfs/null_vnops.c
===================================================================
--- sys/fs/nullfs/null_vnops.c
+++ sys/fs/nullfs/null_vnops.c
@@ -943,3 +943,4 @@
 	.vop_vptofh =		null_vptofh,
 	.vop_add_writecount =	null_add_writecount,
 };
+VFS_VOP_VECTOR_REGISTER(null_vnodeops);
Index: sys/fs/pseudofs/pseudofs_vnops.c
===================================================================
--- sys/fs/pseudofs/pseudofs_vnops.c
+++ sys/fs/pseudofs/pseudofs_vnops.c
@@ -1095,3 +1095,4 @@
 	.vop_write =		pfs_write,
 	/* XXX I've probably forgotten a few that need VOP_EOPNOTSUPP */
 };
+VFS_VOP_VECTOR_REGISTER(pfs_vnodeops);
Index: sys/fs/smbfs/smbfs_vnops.c
===================================================================
--- sys/fs/smbfs/smbfs_vnops.c
+++ sys/fs/smbfs/smbfs_vnops.c
@@ -114,6 +114,7 @@
 	.vop_symlink =		smbfs_symlink,
 	.vop_write =		smbfs_write,
 };
+VFS_VOP_VECTOR_REGISTER(smbfs_vnodeops);
 
 static int
 smbfs_access(ap)
Index: sys/fs/tmpfs/tmpfs_fifoops.c
===================================================================
--- sys/fs/tmpfs/tmpfs_fifoops.c
+++ sys/fs/tmpfs/tmpfs_fifoops.c
@@ -75,3 +75,4 @@
 	.vop_pathconf =                 tmpfs_pathconf,
 	.vop_print =			tmpfs_print,
 };
+VFS_VOP_VECTOR_REGISTER(tmpfs_fifoop_entries);
Index: sys/fs/tmpfs/tmpfs_vnops.c
===================================================================
--- sys/fs/tmpfs/tmpfs_vnops.c
+++ sys/fs/tmpfs/tmpfs_vnops.c
@@ -1636,6 +1636,7 @@
 	.vop_unlock = 			vop_unlock,
 	.vop_islocked = 		vop_islocked,
 };
+VFS_VOP_VECTOR_REGISTER(tmpfs_vnodeop_entries);
 
 /*
  * Same vector for mounts which do not use namecache.
@@ -1644,3 +1645,4 @@
 	.vop_default =			&tmpfs_vnodeop_entries,
 	.vop_lookup =			tmpfs_lookup,
 };
+VFS_VOP_VECTOR_REGISTER(tmpfs_vnodeop_nonc_entries);
Index: sys/fs/udf/udf_vnops.c
===================================================================
--- sys/fs/udf/udf_vnops.c
+++ sys/fs/udf/udf_vnops.c
@@ -97,6 +97,7 @@
 	.vop_strategy =		udf_strategy,
 	.vop_vptofh =		udf_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(udf_vnodeops);
 
 struct vop_vector udf_fifoops = {
 	.vop_default =		&fifo_specops,
@@ -108,6 +109,7 @@
 	.vop_setattr =		udf_setattr,
 	.vop_vptofh =		udf_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(udf_fifoops);
 
 static MALLOC_DEFINE(M_UDFFID, "udf_fid", "UDF FileId structure");
 static MALLOC_DEFINE(M_UDFDS, "udf_ds", "UDF Dirstream structure");
Index: sys/fs/unionfs/union_vnops.c
===================================================================
--- sys/fs/unionfs/union_vnops.c
+++ sys/fs/unionfs/union_vnops.c
@@ -2556,3 +2556,4 @@
 	.vop_vptofh =		unionfs_vptofh,
 	.vop_add_writecount =	unionfs_add_writecount,
 };
+VFS_VOP_VECTOR_REGISTER(unionfs_vnodeops);
Index: sys/kern/uipc_mqueue.c
===================================================================
--- sys/kern/uipc_mqueue.c
+++ sys/kern/uipc_mqueue.c
@@ -2690,6 +2690,7 @@
 	.vop_mkdir		= VOP_EOPNOTSUPP,
 	.vop_rmdir		= VOP_EOPNOTSUPP
 };
+VFS_VOP_VECTOR_REGISTER(mqfs_vnodeops);
 
 static struct vfsops mqfs_vfsops = {
 	.vfs_init 		= mqfs_init,
Index: sys/kern/vfs_default.c
===================================================================
--- sys/kern/vfs_default.c
+++ sys/kern/vfs_default.c
@@ -146,6 +146,7 @@
 	.vop_add_writecount =	vop_stdadd_writecount,
 	.vop_copy_file_range =	vop_stdcopy_file_range,
 };
+VFS_VOP_VECTOR_REGISTER(default_vnodeops);
 
 /*
  * Series of placeholder functions for various error returns for
Index: sys/kern/vfs_lookup.c
===================================================================
--- sys/kern/vfs_lookup.c
+++ sys/kern/vfs_lookup.c
@@ -139,6 +139,10 @@
 	.vop_lock1 =		crossmp_vop_lock1,
 	.vop_unlock =		crossmp_vop_unlock,
 };
+/*
+ * VFS_VOP_VECTOR_REGISTER(crossmp_vnodeops) is not used here since the vnode
+ * gets allocated early. See nameiinit for the direct call below.
+ */
 
 struct nameicap_tracker {
 	struct vnode *dp;
@@ -156,6 +160,7 @@
 	    UMA_ALIGN_PTR, 0);
 	nt_zone = uma_zcreate("rentr", sizeof(struct nameicap_tracker),
 	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
+	vfs_vector_op_register(&crossmp_vnodeops);
 	getnewvnode("crossmp", NULL, &crossmp_vnodeops, &vp_crossmp);
 }
 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nameiinit, NULL);
Index: sys/kern/vfs_subr.c
===================================================================
--- sys/kern/vfs_subr.c
+++ sys/kern/vfs_subr.c
@@ -1558,6 +1558,10 @@
 	int error __unused;
 
 	CTR3(KTR_VFS, "%s: mp %p with tag %s", __func__, mp, tag);
+
+	KASSERT(vops->registered,
+	    ("%s: not registered vector op %p\n", __func__, vops));
+
 	vp = NULL;
 	td = curthread;
 	if (td->td_vp_reserv > 0) {
@@ -4502,6 +4506,7 @@
 	.vop_unlock =	vop_stdunlock,	/* unlock */
 	.vop_islocked =	vop_stdislocked,	/* islocked */
 };
+VFS_VOP_VECTOR_REGISTER(sync_vnodeops);
 
 /*
  * Create a new filesystem syncer vnode for the specified mount point.
Index: sys/sys/vnode.h
===================================================================
--- sys/sys/vnode.h
+++ sys/sys/vnode.h
@@ -954,6 +954,14 @@
 
 void vn_fsid(struct vnode *vp, struct vattr *va);
 
+#include <sys/kernel.h>
+
+#define VFS_VOP_VECTOR_REGISTER(vnodeops) \
+	SYSINIT(vfs_vector_##vnodeops##_f, SI_SUB_VFS, SI_ORDER_ANY, \
+	    vfs_vector_op_register, &vnodeops)
+
+void	vfs_vector_op_register(struct vop_vector *vop);
+
 #endif /* _KERNEL */
 
 #endif /* !_SYS_VNODE_H_ */
Index: sys/tools/vnode_if.awk
===================================================================
--- sys/tools/vnode_if.awk
+++ sys/tools/vnode_if.awk
@@ -323,6 +323,7 @@
 	}
 
 	if (cfile) {
+		funcarr[name] = 1;
 		# Print out the vop_F_vp_offsets structure.  This all depends
 		# on naming conventions and nothing else.
 		printc("static int " name "_vp_offsets[] = {");
@@ -361,9 +362,6 @@
 		printc("");
 		printc("\tVNASSERT(a->a_gen.a_desc == &" name "_desc, a->a_" args[0]",");
 		printc("\t    (\"Wrong a_desc in " name "(%p, %p)\", a->a_" args[0]", a));");
-		printc("\twhile(vop != NULL && \\");
-		printc("\t    vop->"name" == NULL && vop->vop_bypass == NULL)")
-		printc("\t\tvop = vop->vop_default;")
 		printc("\tVNASSERT(vop != NULL, a->a_" args[0]", (\"No "name"(%p, %p)\", a->a_" args[0]", a));")
 		printc("\tSDT_PROBE2(vfs, vop, " name ", entry, a->a_" args[0] ", a);\n");
 		for (i = 0; i < numargs; ++i)
@@ -422,9 +420,44 @@
 		printc("};\n");
 	}
 }
- 
-if (pfile)
+
+if (cfile) {
+	printc("void");
+	printc("vfs_vector_op_register(struct vop_vector *orig_vop)");
+	printc("{");
+	printc("\tstruct vop_vector *vop;");
+	printc("");
+	printc("\tif (orig_vop->registered)");
+	printc("\t\tpanic(\"%s: vop_vector %p already registered\",")
+	printc("\t\t    __func__, orig_vop);");
+	printc("");
+	for (name in funcarr) {
+		printc("\tvop = orig_vop;");
+		printc("\twhile (vop != NULL && \\");
+		printc("\t    vop->"name" == NULL && vop->vop_bypass == NULL)")
+		printc("\t\tvop = vop->vop_default;")
+		printc("\tif (vop != NULL)");
+		printc("\t\torig_vop->"name" = vop->"name";");
+		printc("");
+	}
+	printc("\tvop = orig_vop;");
+	printc("\twhile (vop != NULL && vop->vop_bypass == NULL)")
+	printc("\t\tvop = vop->vop_default;")
+	printc("\tif (vop != NULL)");
+	printc("\t\torig_vop->vop_bypass = vop->vop_bypass;");
+	printc("");
+	printc("\torig_vop->registered = true;");
+	printc("}")
+}
+
+if (hfile) {
+	printh("void vfs_vector_op_register(struct vop_vector *orig_vop);");
+}
+
+if (pfile) {
+	printp("\tbool\tregistered;")
 	printp("};")
+}
  
 if (hfile)
 	close(hfile);
Index: sys/ufs/ffs/ffs_vnops.c
===================================================================
--- sys/ufs/ffs/ffs_vnops.c
+++ sys/ufs/ffs/ffs_vnops.c
@@ -140,6 +140,7 @@
 	.vop_write =		ffs_write,
 	.vop_vptofh =		ffs_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ffs_vnodeops1);
 
 struct vop_vector ffs_fifoops1 = {
 	.vop_default =		&ufs_fifoops,
@@ -148,6 +149,7 @@
 	.vop_lock1 =		ffs_lock,
 	.vop_vptofh =		ffs_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ffs_fifoops1);
 
 /* Global vfs data structures for ufs. */
 struct vop_vector ffs_vnodeops2 = {
@@ -168,6 +170,7 @@
 	.vop_setextattr =	ffs_setextattr,
 	.vop_vptofh =		ffs_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ffs_vnodeops2);
 
 struct vop_vector ffs_fifoops2 = {
 	.vop_default =		&ufs_fifoops,
@@ -184,6 +187,7 @@
 	.vop_setextattr =	ffs_setextattr,
 	.vop_vptofh =		ffs_vptofh,
 };
+VFS_VOP_VECTOR_REGISTER(ffs_fifoops2);
 
 /*
  * Synch an open file.
Index: sys/ufs/ufs/ufs_vnops.c
===================================================================
--- sys/ufs/ufs/ufs_vnops.c
+++ sys/ufs/ufs/ufs_vnops.c
@@ -2771,6 +2771,7 @@
 	.vop_aclcheck =		ufs_aclcheck,
 #endif
 };
+VFS_VOP_VECTOR_REGISTER(ufs_vnodeops);
 
 struct vop_vector ufs_fifoops = {
 	.vop_default =		&fifo_specops,
@@ -2801,3 +2802,4 @@
 	.vop_aclcheck =		ufs_aclcheck,
 #endif
 };
+VFS_VOP_VECTOR_REGISTER(ufs_fifoops);