linux-ext4 - Re: Atomic non-durable file write API

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Message-ID: <AANLkTin361ZYPc7X5++E0DPZ1_Ndt5naprXeGJJJtgqy@mail.gmail.com>
Date:	Tue, 28 Dec 2010 23:06:15 +0100
From:	Olaf van der Spek <olafvdspek@...il.com>
To:	Greg Freemyer <greg.freemyer@...il.com>
Cc:	Neil Brown <neilb@...e.de>,
	Christian Stroetmann <stroetmann@...olinux.com>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-ext4@...r.kernel.org, "Ted Ts'o" <tytso@....edu>,
	Nick Piggin <npiggin@...il.com>
Subject: Re: Atomic non-durable file write API

On Tue, Dec 28, 2010 at 11:00 PM, Greg Freemyer <greg.freemyer@...il.com> wrote:
> create temp file
> write out new data
> delete old file
> rename temp file to primary name
> ===
>
> If so there is still a little window of vulnerability where the whole
> file can be lost.  (Or at least only the temp file is present).

Delete isn't used, rename will overwrite the old file. So it's safe.
Meta-data is probably lost, file owner is certainly lost.

Olaf
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