ext4 - getting at birth time (file create time) and getting/setting nanosecond time stamps and utime

Steve French smfrench at gmail.com
Tue Oct 20 15:11:15 MDT 2009

On Tue, Oct 20, 2009 at 3:59 PM, Sunil Mushran <sunil.mushran at oracle.com> wrote:
> Steve French wrote:
>> So, are we ready for Mingming or one of the ext4 developers to propose
>> a patch for this via xattrs (I can do a similar one for cifs).
>> Sounds like various have said:
>> 1) xattrs instead of ioctl
>> 2) get of create time allowed by default, but set of create time limited
>> But for the second part of this - how should we set nanosecond
>> timestamps for the others (or in Samba's case, rounded to 100
>> nanoseconds for DCE time) ... a millisecond granularity for utimes is
>> a very long time these days.
> What's wrong with stat(2)? AFAIK, it supports nanoseconds.

An earlier post from Mingming IIRC noted that utimes does not support
setting nanosecond timestamps (e.g. write time).

"The function utime() allows specification of time stamps with a
resolution of 1 second. ... The function utimes() is similar, but the
times argument allows a reso lution of 1 microsecond for the
timestamps. "   1 millisecond is not sufficient, and as a result Samba
has to store duplicate time stamps (in Samba specific xattrs) which we
would like to avoid wherever possible



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