From: Olaf van der Spek Subject: Re: Atomic non-durable file write API Date: Sun, 19 Dec 2010 17:39:01 +0100 Message-ID: References: <4D0A7278.3080506@gmail.com> <1292710543.17128.14.camel@nayuki> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Ric Wheeler , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: Calvin Walton Return-path: Received: from mail-fx0-f43.google.com ([209.85.161.43]:61385 "EHLO mail-fx0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756863Ab0LSQjD convert rfc822-to-8bit (ORCPT ); Sun, 19 Dec 2010 11:39:03 -0500 In-Reply-To: <1292710543.17128.14.camel@nayuki> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, Dec 18, 2010 at 11:15 PM, Calvin Walton wrote: > Hmm. I=E2=80=99m doing a little interpretation of what Olaf said here= ; but I > think you may have misunderstood the question? > > He doesn=E2=80=99t care about whether or not the file is securely wri= tten to > disk (durable); however he doesn=E2=80=99t want to see any partially = written > files. In other words, something like > > =C2=A0 =C2=A0 1. Write to temp file > =C2=A0 =C2=A0 2. Rename temp file over original file Meta data, including file owner, should be preserved. Ideally, no temp files should be visible either. > Where the rename is only committed to disk once the entire contents o= f > the file have been written securely =E2=80=93 whenever that may event= ually > happen. > > He doesn=E2=80=99t want to synchronously wait for the file to be writ= ten, > because the new data isn=E2=80=99t particularly important. The only i= mportant > thing is that the file either contains the old or new data after a > filesystem crash; not incomplete data. So, it=E2=80=99s more of an or= dering > problem, I think? (Analogous to putting some sort of barrier between = the > file write/close and the file rename to maintain ordering.) > > Hopefully I=E2=80=99ve interpreted the original question correctly, b= ecause this > is something I would find interesting as well. Yes, you did. Olaf -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html