From: Dave Chinner Subject: Re: Atomic non-durable file write API Date: Fri, 24 Dec 2010 09:43:09 +1100 Message-ID: <20101223224309.GH18264@dastard> 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: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org To: Olaf van der Spek Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Dec 23, 2010 at 04:49:53PM +0100, Olaf van der Spek wrote: > On Sun, Dec 19, 2010 at 5:39 PM, Olaf van der Spek wrote: > > 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 h= ere; but I > >> think you may have misunderstood the question? > >> > >> He doesn=E2=80=99t care about whether or not the file is securely = written to > >> disk (durable); however he doesn=E2=80=99t want to see any partial= ly 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 content= s of > >> the file have been written securely =E2=80=93 whenever that may ev= entually > >> happen. > >> > >> He doesn=E2=80=99t want to synchronously wait for the file to be w= ritten, > >> because the new data isn=E2=80=99t particularly important. The onl= y important > >> 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= ordering > >> problem, I think? (Analogous to putting some sort of barrier betwe= en the > >> file write/close and the file rename to maintain ordering.) > >> > >> Hopefully I=E2=80=99ve interpreted the original question correctly= , because this > >> is something I would find interesting as well. > > > > Yes, you did. >=20 > Somebody? So you are looking for something like: http://developer.apple.com/library/mac/#DOCUMENTATION/Darwin/Reference/= ManPages/man2/exchangedata.2.html ? Cheers, Dave. --=20 Dave Chinner david@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html