Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755594AbYGIG4o (ORCPT ); Wed, 9 Jul 2008 02:56:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752049AbYGIG4d (ORCPT ); Wed, 9 Jul 2008 02:56:33 -0400 Received: from casper.infradead.org ([85.118.1.10]:33549 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751269AbYGIG4c (ORCPT ); Wed, 9 Jul 2008 02:56:32 -0400 Date: Tue, 8 Jul 2008 23:55:02 -0700 From: Arjan van de Ven To: Miklos Szeredi Cc: miklos@szeredi.hu, 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 Subject: Re: [PATCH 3/3] Add timeout feature Message-ID: <20080708235502.1c52a586@infradead.org> In-Reply-To: References: <20080630212450t-sato@mail.jp.nec.com> <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> Organization: Intel X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1476 Lines: 38 On Wed, 09 Jul 2008 08:48:42 +0200 Miklos Szeredi wrote: > On Tue, 8 Jul 2008, Arjan van de Ven wrote: > > nah he needs to do > > > > make_snapshot ; backup-command ; unref_snapshot. > > > > freezing isn't the right solution for the backup problem ;) > > Confused, what's freezing _is_ for then? Patch description says: > > Currently, ext3 in mainline Linux doesn't have the freeze feature > which suspends write requests. So, we cannot take a backup which > keeps the filesystem's consistency with the storage device's features > (snapshot and replication) while it is mounted. I tihnk the idea there is freeze . do the snapshot op . unfreeze . make backup of snapshot one can argue about the need of doing the first 3 steps via a userland loop; it sure sounds like one needs to be really careful to not do any writes to the fs from the app that does snapshots (and that includes doing any syscalls in the kernel that allocate memory.. just because that already could cause unrelated data to be written from inside the app. Not fun.) -- If you want to reach me at my work email, use arjan@linux.intel.com For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/