EXT4_EPOCH_MASK
u32 extra = ((ts.tv_sec - (s32)ts.tv_sec) >> 32) & EXT4_EPOCH_MASK;
if (unlikely(extra & cpu_to_le32(EXT4_EPOCH_MASK)))
ts.tv_sec += (u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK) << 32;