From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sunil Mushran Subject: Re: ext4 - getting at birth time (file create time) and getting/setting nanosecond time stamps and utime Date: Tue, 20 Oct 2009 14:23:45 -0700 Message-ID: <4ADE2A61.5040505@oracle.com> References: <524f69650910191017j7883ed7bvdb0329d1a73f34e4@mail.gmail.com> <524f69650910191245t2eb7ffb2r770a7373ec2ba1e3@mail.gmail.com> <5715838A-4568-4273-B1C1-983B348580B6@sun.com> <524f69650910191524k5c9d766fu430c4f7b17d86952@mail.gmail.com> <890110E9-FA69-4356-9BEB-925F98487C52@sun.com> <4ADDB09D.5000707@hp.com> <6E5D19DA-64C5-4A44-9DF4-BEF2AA8DD8AB@sun.com> <524f69650910201349w20a3145cm6b88cd4029912b6b@mail.gmail.com> <4ADE24C2.20009@oracle.com> <524f69650910201411j3dc4897bic8a042cb17fcede8@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , jim owens , linux-fsdevel , samba-technical To: Steve French Return-path: Received: from acsinet12.oracle.com ([141.146.126.234]:25869 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751026AbZJTVZY (ORCPT ); Tue, 20 Oct 2009 17:25:24 -0400 In-Reply-To: <524f69650910201411j3dc4897bic8a042cb17fcede8@mail.gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Steve French wrote: > On Tue, Oct 20, 2009 at 3:59 PM, Sunil Mushran 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 If you are trying to update it, you can use utimensat(2).