From: Greg Freemyer Subject: Re: [PATCH 02/18] xstat: Add a pair of system calls to make extended file stats available [ver #6] Date: Thu, 22 Jul 2010 12:06:22 -0400 Message-ID: References: <20100715021709.5544.64506.stgit@warthog.procyon.org.uk> <20100715021712.5544.44845.stgit@warthog.procyon.org.uk> <30448.1279800887@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Volker.Lendecke-3ekOc4rQMZmzQB+pC5nmwQ@public.gmane.org, David Howells , Jan Engelhardt , linux-cifs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Linus Torvalds Return-path: In-Reply-To: Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Thu, Jul 22, 2010 at 11:47 AM, Linus Torvalds wrote: > On Thu, Jul 22, 2010 at 8:36 AM, Volker Lendecke > wrote: >> >> The nice thing about this is also that if this is supposed >> to be fully usable for Windows clients, the birthtime needs >> to be changeable. That's what NTFS semantics gives you, thus >> Windows clients tend to require it. > > Ok. So it's not really a creation date, exactly the same way ctime > isn't at all a creation date. > > And maybe that actually hints at a better solution: maybe a better > model is to create a new per-thread flag that says "do ctime updates > the way windows does them". > > So instead of adding another "btime" - which isn't actually what even > windows does - just admit that the _real_ issue is that Unix and > Windows semantics are different for the pre-existing "ctime". > > The fact is, windows has "access time", "modification time" and > "creation time" _exactly_ like UNIX. It's just that the ctime has > slightly different semantics in windows vs unix. So quite frankly, > it's totally insane to introduce a "birthtime", when that isn't even > what windows wants, just because people cannot face the actual real > difference. > > Tell me why we shouldn't just do this right? > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Linus I haven't been keeping up with this thread, but I believe NTFS has a number of timestamps, not just 3. This blog post references 8 in the left hand column. The 4 standard (most common) ones are: =46ile last access =46ile last modified =46ile created MFT last modified My understanding is that "MFT last modified" has semantics very similar to Linux ctime. But there is not a generic equivalent to NTFS created. Thus if trying to have the Linux kernel match NTFS semantics for the benefit of Samba is the goal, it seems a new field should be preferred instead of having linux ctime try to do different jobs. Greg