From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Xin Zhao" Subject: how do versioning filesystems take snapshot of opened files? Date: Tue, 3 Jul 2007 01:28:57 -0400 Message-ID: <4ae3c140707022228u2b5098c5v766b9dc9a7e09ea1@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: linux-fsdevel , linux-kernel Return-path: Received: from nz-out-0506.google.com ([64.233.162.226]:53828 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751868AbXGCF27 (ORCPT ); Tue, 3 Jul 2007 01:28:59 -0400 Received: by nz-out-0506.google.com with SMTP id s18so1113828nze for ; Mon, 02 Jul 2007 22:28:58 -0700 (PDT) Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Hi, If a file is already opened when snapshot command is issued, the file itself could be in an inconsistent state already. Before the file is closed, maybe part of the file contains old data, the rest contains new data. How does a versioning filesystem guarantee that the file snapshot is in a consistent state in this case? I googled it but didn't find any answer. Can someone explain it a little bit? Thanks