Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755586Ab0KUUUK (ORCPT ); Sun, 21 Nov 2010 15:20:10 -0500 Received: from cantor.suse.de ([195.135.220.2]:47241 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753419Ab0KUUUH (ORCPT ); Sun, 21 Nov 2010 15:20:07 -0500 Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation From: James Bottomley To: Valdis.Kletnieks@vt.edu Cc: Mark Lord , Chris Mason , Christoph Hellwig , Matthew Wilcox , Josef Bacik , Lukas Czerner , tytso , linux-ext4 , linux-kernel , linux-fsdevel , sandeen In-Reply-To: <36056.1290366424@localhost> References: <1290065809-3976-1-git-send-email-lczerner@redhat.com> <20101118130630.GJ6178@parisc-linux.org> <20101118134804.GN5618@dhcp231-156.rdu.redhat.com> <20101118141957.GK6178@parisc-linux.org> <20101118142918.GA18510@infradead.org> <1290100750.3041.72.camel@mulgrave.site> <4CE59C9E.6050902@teksavvy.com> <1290177488-sup-6540@think> <4CE68F80.7000607@teksavvy.com> <36056.1290366424@localhost> Content-Type: text/plain; charset="UTF-8" Date: Sun, 21 Nov 2010 14:20:00 -0600 Message-ID: <1290370800.3017.6.camel@mulgrave.site> Mime-Version: 1.0 X-Mailer: Evolution 2.30.1.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1441 Lines: 31 On Sun, 2010-11-21 at 14:07 -0500, Valdis.Kletnieks@vt.edu wrote: > On Fri, 19 Nov 2010 09:53:52 EST, Mark Lord said: > > On 10-11-19 09:40 AM, Chris Mason wrote: > > > > > > We've been told that online and constant trimming is the default in > > > windows7. The ssds are most likely to just start ignoring the trims > > > they can't service efficiently. > > > > Win7 collects multiple TRIM ranges over time and batches them as single TRIMs > > (as reported to me by an SSD vendor who traced it with a SATA analyzer, > > and who also apparently has "inside info"). > > What should happen if we have (for instance) a "collect 64 trims at a time" policy, > and the system crashes at trim number 47? (Probably not an issue if you're > doing non-deterministic trim, but is an exposure if you're relying on deterministic > trim for security reasons) I think it's about the third time in the thread this has been said but just in case anyone else missed it: TRIM != SECURE ERASE. TRIM/UNMAP/WRITE_SAME are used to provide optional information about which blocks the filesystem doesn't care about. They have no bearing on information security which is preserved by separate mechanisms. James -- 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/