Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	(wersja 255320)
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	(kopia robocza)
@@ -4302,6 +4302,11 @@
 	szp = VTOZ(svp);
 	ZFS_VERIFY_ZP(szp);
 
+	if (szp->z_pflags & (ZFS_APPENDONLY | ZFS_IMMUTABLE | ZFS_READONLY)) {
+		ZFS_EXIT(zfsvfs);
+		return (SET_ERROR(EPERM));
+	}
+
 	/*
 	 * We check z_zfsvfs rather than v_vfsp here, because snapshots and the
 	 * ctldir appear to have the same v_vfsp.