ZVOL_RDONLY
if (!(bp->b_flags & B_READ) && (zv->zv_flags & ZVOL_RDONLY)) {
if (zv->zv_flags & ZVOL_RDONLY)
zv->zv_flags |= ZVOL_RDONLY;
zv->zv_flags |= ZVOL_RDONLY;
zv->zv_flags &= ~ZVOL_RDONLY;
!(zv->zv_flags & ZVOL_RDONLY))
if ((flag & FWRITE) && (zv->zv_flags & ZVOL_RDONLY)) {