From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f180.google.com ([209.85.192.180]:33834 "EHLO mail-pf0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751259AbdAPABh (ORCPT ); Sun, 15 Jan 2017 19:01:37 -0500 Received: by mail-pf0-f180.google.com with SMTP id e4so10080160pfg.1 for ; Sun, 15 Jan 2017 16:01:36 -0800 (PST) Message-ID: <1484524890.27533.16.camel@dubeyko.com> Subject: Re: [LSF/MM TOPIC] online filesystem repair From: Viacheslav Dubeyko To: "Darrick J. Wong" , lsf-pc@lists.linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, Vyacheslav.Dubeyko@wdc.com Date: Sun, 15 Jan 2017 16:01:30 -0800 In-Reply-To: <20170114075452.GJ14033@birch.djwong.org> References: <20170114075452.GJ14033@birch.djwong.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, 2017-01-13 at 23:54 -0800, Darrick J. Wong wrote: > Hi, > > I've been working on implementing online metadata scrubbing and > repair > in XFS.  Most of the code is self contained inside XFS, but there's a > small amount of interaction with the VFS freezer code that has to > happen > in order to shut down the filesystem to rebuild the extent backref > records.  It might be interesting to discuss the (fairly slight) > requirements upon the VFS to support repairs, and/or have a BoF to > discuss how to build an online checker if any of the other > filesystems > are interested in this. > How do you imagine a generic way to support repairs for different file systems? From one point of view, to have generic way of the online file system repairing could be the really great subsystem. But, from another point of view, every file system has own architecture, own set of metadata and own way to do fsck check/recovering. As far as I can judge, there are significant amount of research efforts in this direction (Recon [1], [2], for example). But we still haven't any real general online file system repair subsystem in the Linux kernel. Do you have some new insight? What's difference of your vision? If we have online file system repair subsystem then how file system driver will need to interact with the goal to make internal repairing? Thanks, Vyacheslav Dubeyko. [1] http://www.eecg.toronto.edu/~ashvin/publications/recon-fs-consistency-runtime.pdf [2] https://www.researchgate.net/publication/269300836_Managing_the_file_system_from_the_kernel