From: Dave Chinner Subject: Re: [PATCH 3/3] Add timeout feature Date: Wed, 9 Jul 2008 16:59:50 +1000 Message-ID: <20080709065950.GR11558@disturbed> References: <20080701081026.GB16691@infradead.org> <20080707110730.GG5643@ucw.cz> <20080708231026.GP11558@disturbed> <20080708232031.GE18195@elf.ucw.cz> <20080709005254.GQ11558@disturbed> <20080709010922.GE9957@mit.edu> <20080709061621.GA5260@infradead.org> <20080708234120.5072111f@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Miklos Szeredi , hch@infradead.org, tytso@mit.edu, pavel@suse.cz, t-sato@yk.jp.nec.com, akpm@linux-foundation.org, viro@ZenIV.linux.org.uk, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, axboe@kernel.dk, mtk.manpages@googlemail.com To: Arjan van de Ven Return-path: Received: from ipmail01.adl6.internode.on.net ([203.16.214.146]:58871 "EHLO ipmail01.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752551AbYGIG77 (ORCPT ); Wed, 9 Jul 2008 02:59:59 -0400 Content-Disposition: inline In-Reply-To: <20080708234120.5072111f@infradead.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Jul 08, 2008 at 11:41:20PM -0700, Arjan van de Ven wrote: > On Wed, 09 Jul 2008 08:22:56 +0200 > Miklos Szeredi wrote: > > > On Wed, Jul 09, 2008 at 08:13:21AM +0200, Miklos Szeredi wrote: > > > > This would mean that freeze and thaw will have to be done on the > > > > same file descriptor, but this isn't unreasonable to expect, is > > > > it? > > > > > > It is certainly not the current use case, where you run one command > > > to freeze the filesystem and another one to unfreeze it. > > > > So instead of > > > > freeze_fs mountpoint > > backup-command > > unfreeze_fs mountpoint > > > > the user would have do to > > > > run_freezed mountpoint backup-command > > > > I find the second one nicer, regardless of any reliability issues. > > nah he needs to do > > make_snapshot ; backup-command ; unref_snapshot. > > freezing isn't the right solution for the backup problem ;) You're forgetting that to take a snapshot you generally need to freeze the filesystem. ;) i.e: freeze; make_snapshot; unfreeze backup-command unref_snapshot Yes, dm_snapshot does the freeze/snapshot/unfreeze for you, but the point is there is a freeze in the example you gave. The argument against Miklos' version is that there may be multiple commands to execute while the fs is frozen. Cheers, Dave. -- Dave Chinner david@fromorbit.com