From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: JFYI: ext4 bug triggerable by kvm Date: Mon, 16 Aug 2010 09:43:09 -0500 Message-ID: <4C694E7D.3060600@codemonkey.ws> References: <4C694483.5010903@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: KVM list , Kevin Wolf To: Michael Tokarev Return-path: Received: from mail-yw0-f46.google.com ([209.85.213.46]:62805 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754147Ab0HPOnQ (ORCPT ); Mon, 16 Aug 2010 10:43:16 -0400 Received: by ywh1 with SMTP id 1so1890451ywh.19 for ; Mon, 16 Aug 2010 07:43:16 -0700 (PDT) In-Reply-To: <4C694483.5010903@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 08/16/2010 09:00 AM, Michael Tokarev wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=16165 > > When a (raw) guest image is placed on an ext4 filesystem, > it is possible to get data corruption, now due to ext4 > bug, not kvm bug. > Yeah, there appears to be a few O_DIRECT related issues with ext4. AFAIK, a preallocated raw image should be safe though which is probably the only time you should use O_DIRECT. > Also, ext4 is _very_ slow on O_SYNC writes (which is > used in kvm with default cache). > Yeah, we probably need to switch to sync_file_range() to avoid the journal commit on every write. Regards, Anthony Liguori > JFYI. > > /mjt > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >