4 files changed, 40 insertions, 7 deletions

diff --git a/sys/fs/nullfs/null.h b/sys/fs/nullfs/null.h
index 3ae0cd02b2b6..eebf6da571b8 100644
--- a/sys/fs/nullfs/null.h
+++ b/sys/fs/nullfs/null.h
@@ -37,7 +37,8 @@
 #ifndef	FS_NULL_H
 #define	FS_NULL_H
 
-#define	NULLM_CACHE	0x0001
+#define	NULLM_CACHE		0x0001
+#define	NULLM_NOUNPBYPASS	0x0002
 
 struct null_mount {
 	struct mount	*nullm_vfs;
@@ -80,6 +81,16 @@ struct vnode *null_checkvp(struct vnode *vp, char *fil, int lno);
 #endif
 
 extern struct vop_vector null_vnodeops;
+extern struct vop_vector null_vnodeops_no_unp_bypass;
+
+static inline bool
+null_is_nullfs_vnode(struct vnode *vp)
+{
+	const struct vop_vector *op;
+
+	op = vp->v_op;
+	return (op == &null_vnodeops || op == &null_vnodeops_no_unp_bypass);
+}
 
 #ifdef MALLOC_DECLARE
 MALLOC_DECLARE(M_NULLFSNODE);
diff --git a/sys/fs/nullfs/null_subr.c b/sys/fs/nullfs/null_subr.c
index 546f0aea3766..b0e3d15b4789 100644
--- a/sys/fs/nullfs/null_subr.c
+++ b/sys/fs/nullfs/null_subr.c
@@ -212,7 +212,9 @@ null_nodeget(struct mount *mp, struct vnode *lowervp, struct vnode **vpp)
 	 */
 	xp = malloc(sizeof(struct null_node), M_NULLFSNODE, M_WAITOK);
 
-	error = getnewvnode("nullfs", mp, &null_vnodeops, &vp);
+	error = getnewvnode("nullfs", mp, (MOUNTTONULLMOUNT(mp)->nullm_flags &
+	    NULLM_NOUNPBYPASS) != 0 ? &null_vnodeops_no_unp_bypass :
+	    &null_vnodeops, &vp);
 	if (error) {
 		vput(lowervp);
 		free(xp, M_NULLFSNODE);
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index 8d980932623d..8b9e04775449 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -89,6 +89,10 @@ nullfs_mount(struct mount *mp)
 	char *target;
 	int error, len;
 	bool isvnunlocked;
+	static const char cache_opt_name[] = "cache";
+	static const char nocache_opt_name[] = "nocache";
+	static const char unixbypass_opt_name[] = "unixbypass";
+	static const char nounixbypass_opt_name[] = "nounixbypass";
 
 	NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
 
@@ -120,7 +124,7 @@ nullfs_mount(struct mount *mp)
 	/*
 	 * Unlock lower node to avoid possible deadlock.
 	 */
-	if (mp->mnt_vnodecovered->v_op == &null_vnodeops &&
+	if (null_is_nullfs_vnode(mp->mnt_vnodecovered) &&
 	    VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
 		VOP_UNLOCK(mp->mnt_vnodecovered);
 		isvnunlocked = true;
@@ -154,7 +158,7 @@ nullfs_mount(struct mount *mp)
 	/*
 	 * Check multi null mount to avoid `lock against myself' panic.
 	 */
-	if (mp->mnt_vnodecovered->v_op == &null_vnodeops) {
+	if (null_is_nullfs_vnode(mp->mnt_vnodecovered)) {
 		nn = VTONULL(mp->mnt_vnodecovered);
 		if (nn == NULL || lowerrootvp == nn->null_lowervp) {
 			NULLFSDEBUG("nullfs_mount: multi null mount?\n");
@@ -209,9 +213,10 @@ nullfs_mount(struct mount *mp)
 		MNT_IUNLOCK(mp);
 	}
 
-	if (vfs_getopt(mp->mnt_optnew, "cache", NULL, NULL) == 0) {
+	if (vfs_getopt(mp->mnt_optnew, cache_opt_name, NULL, NULL) == 0) {
 		xmp->nullm_flags |= NULLM_CACHE;
-	} else if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0) {
+	} else if (vfs_getopt(mp->mnt_optnew, nocache_opt_name, NULL,
+	    NULL) == 0) {
 		;
 	} else if (null_cache_vnodes &&
 	    (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) == 0) {
@@ -223,6 +228,13 @@ nullfs_mount(struct mount *mp)
 		    &xmp->notify_node);
 	}
 
+	if (vfs_getopt(mp->mnt_optnew, unixbypass_opt_name, NULL, NULL) == 0) {
+		;
+	} else if (vfs_getopt(mp->mnt_optnew, nounixbypass_opt_name, NULL,
+	    NULL) == 0) {
+		xmp->nullm_flags |= NULLM_NOUNPBYPASS;
+	}
+
 	if (lowerrootvp == mp->mnt_vnodecovered) {
 		vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE);
 		lowerrootvp->v_vflag |= VV_CROSSLOCK;
diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
index 41915da7f13c..2e34b77a5a7e 100644
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -258,7 +258,7 @@ null_bypass(struct vop_generic_args *ap)
 		 * that aren't.  (We must always map first vp or vclean fails.)
 		 */
 		if (i != 0 && (*this_vp_p == NULLVP ||
-		    (*this_vp_p)->v_op != &null_vnodeops)) {
+		    !null_is_nullfs_vnode(*this_vp_p))) {
 			old_vps[i] = NULLVP;
 		} else {
 			old_vps[i] = *this_vp_p;
@@ -1192,3 +1192,11 @@ struct vop_vector null_vnodeops = {
 	.vop_copy_file_range =	VOP_PANIC,
 };
 VFS_VOP_VECTOR_REGISTER(null_vnodeops);
+
+struct vop_vector null_vnodeops_no_unp_bypass = {
+	.vop_default =		&null_vnodeops,
+	.vop_unp_bind =		vop_stdunp_bind,
+	.vop_unp_connect =	vop_stdunp_connect,
+	.vop_unp_detach =	vop_stdunp_detach,
+};
+VFS_VOP_VECTOR_REGISTER(null_vnodeops_no_unp_bypass);