FS_COMMON_FL
mask &= FS_COMMON_FL;
fa->flags |= old_ma.flags & ~FS_COMMON_FL;
BUILD_BUG_ON(OVL_COPY_FS_FLAGS_MASK & ~FS_COMMON_FL);
BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);