On Mon, Jun 18, 2018 at 5:50 PM, Ard Biesheuvel
<ard.biesheuvel@xxxxxxxxxx> wrote:
> On 18 June 2018 at 17:49, Arnd Bergmann <arnd@xxxxxxxx> wrote:
>> On Mon, Jun 18, 2018 at 5:47 PM, Ard Biesheuvel
>> <ard.biesheuvel@xxxxxxxxxx> wrote:
>>> On 18 June 2018 at 16:17, Arnd Bergmann <arnd@xxxxxxxx> wrote:
>>
>>>> - atomic64_set(&seq, ((u64)get_seconds()) << 32);
>>>> + if (!atomic64_read(&seq)) {
>>>> + time64_t time = ktime_get_real_seconds();
>>>> +
>>>> + /*
>>>> + * This code is unlikely to still be needed in year 2106,
>>>> + * but just in case, let's use a few more bits for timestamps
>>>> + * after y2038 to be sure they keep increasing monotonically
>>>> + * for the next few hundred years...
>>>> + */
>>>> + if (time < 0x80000000)
>>>> + atomic64_set(&seq, (ktime_get_real_seconds()) << 32);
>>>> + else
>>>> + atomic64_set(&seq, 0x8000000000000000ull |
>>>> + ktime_get_real_seconds() << 24);
>>>> + }
>>>
>>> Given that these values are never decoded and interpreted as
>>> timestamps, can't we simply switch to the second flavour immediately?
>>
>> I considered that, but the downside would be that all future filenames would
>> come before all past file names.
>
> Won't we have that same problem in 2038?
No, it goes from 0x7fffffff00000000 to 0x8000000000000000, followed
by 0x8000000001000000.
Arnd
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