Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755370Ab0H3UVb (ORCPT ); Mon, 30 Aug 2010 16:21:31 -0400 Received: from cantor.suse.de ([195.135.220.2]:52408 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753902Ab0H3UV3 (ORCPT ); Mon, 30 Aug 2010 16:21:29 -0400 Date: Mon, 30 Aug 2010 22:20:34 +0200 From: Jan Kara To: Jeff Moyer Cc: Jan Kara , Tejun Heo , Christoph Hellwig , jaxboe@fusionio.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, linux-raid@vger.kernel.org, James.Bottomley@suse.de, tytso@mit.edu, chris.mason@oracle.com, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp, dm-devel@redhat.com, vst@vlnb.net, rwheeler@redhat.com, hare@suse.de, neilb@suse.de, rusty@rustcorp.com.au, mst@redhat.com, jeremy@goop.org, snitzer@redhat.com, k-ueda@ct.jp.nec.com, Christoph Hellwig Subject: Re: [PATCH 26/30] ext4: do not send discards as barriers Message-ID: <20100830202034.GB12226@quack.quadriga.com> References: <1282751267-3530-1-git-send-email-tj@kernel.org> <1282751267-3530-27-git-send-email-tj@kernel.org> <20100825155842.GA3229@lst.de> <20100825160032.GC3229@lst.de> <4C753D75.2010305@kernel.org> <20100825200223.GE2738@quack.suse.cz> <4C76250B.6060800@kernel.org> <20100827173147.GA12374@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1410 Lines: 30 On Mon 30-08-10 15:56:43, Jeff Moyer wrote: > Jan Kara writes: > > > An update: I've set up an ext4 barrier testing in KVM - run fsstress, > > kill KVM at some random moment and check that the filesystem is consistent > > (kvm is run in cache=writeback mode to simulate disk cache). About 70 runs > > But doesn't your "disk cache" survive the "power cycle" of your guest? Yes, you're right. Thinking about it now the test setup was wrong because it didn't refuse writes to the VM's data partition after the moment I killed KVM. Thanks for catching this. I will probably have to use the fault injection on the host to disallow writing the device at a certain moment. Or does somebody have a better option? My setup is that I have a dedicated partition / drive for a filesystem which is written to from a guest kernel running under KVM. I have set it up using virtio driver with cache=writeback so that the host caches the writes in a similar way disk caches them. At some point I just kill the qemu-kvm process and at that point I'd like to also throw away data cached by the host... Honza -- Jan Kara SUSE Labs, CR -- 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/