linux-kernel - Re: [PATCH 02/18] xstat: Add a pair of system calls to make extended file stats available [ver #6]

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Message-ID: <20100805235218.GB31233@jeremy-laptop>
Date:	Thu, 5 Aug 2010 16:52:18 -0700
From:	Jeremy Allison <jra@...ba.org>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	utz lehmann <lkml123@...4n2c.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jeremy Allison <jra@...ba.org>, Volker.Lendecke@...net.de,
	David Howells <dhowells@...hat.com>,
	Jan Engelhardt <jengelh@...ozas.de>,
	linux-cifs@...r.kernel.org, linux-nfs@...r.kernel.org,
	samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org,
	viro@...iv.linux.org.uk, linux-fsde@...per.es
Subject: Re: [PATCH 02/18] xstat: Add a pair of system calls to make
 extended  file stats available [ver #6]

On Sun, Aug 01, 2010 at 09:25:29AM -0400, Jeff Layton wrote:
> On Fri, 30 Jul 2010 23:22:58 +0200
> utz lehmann <lkml123@...4n2c.de> wrote:
> 
> > On Thu, 2010-07-22 at 09:40 -0700, Linus Torvalds wrote:
> > > But the fact is, th Unix ctime semantics are insane and largely
> > > useless. There's a damn good reason almost nobody uses ctime under
> > > unix.
> > > 
> > > So what I'm suggesting is that we have a flag - either per-process or
> > > per-mount - that just says "use windows semantics for ctime".
> > 
> > When abusing an existing time stamp use atime not ctime please.
> > ctime has it's uses. atime was just a mistake and is nearly useless.
> > 
> > And with noatime we already have creation time semantics for atime.
> > 
> 
> Ugh. Honestly all of this talk of abusing different time fields seems
> like craziness to me. It's going to be very hard to do that without
> breaking *something*. There's also very little reason to do this when
> xattrs are a much cleaner approach.
> 
> Neil Brown has put forth a very reasoned justification for putting the
> birthtime in an xattr. After reading it, I think that makes more sense
> than anything. It's also something that can be done without any extra
> infrastructure. If at some point in the future we get an xstat-like
> syscall then we can always add birthtime to that as well.

Just my 2 cents (as a Samba server implementor). I *hate* the idea
of adding a "virtual" EA for birthtime. If you're going to add it,
just add it to the stat struct like *BSD does. Don't abuse the other
time fields, it's a new one.

Jeff, please don't advocate for an EA for the Samba server to use.
Don't add it as an EA. It's *not* an EA, it's a timestamp.

Jeremy.
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