Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751918Ab3FHJR4 (ORCPT ); Sat, 8 Jun 2013 05:17:56 -0400 Received: from smtp.gentoo.org ([140.211.166.183]:60991 "EHLO smtp.gentoo.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751571Ab3FHJRx (ORCPT ); Sat, 8 Jun 2013 05:17:53 -0400 Message-ID: <51B2F694.7010008@gentoo.org> Date: Sat, 08 Jun 2013 05:17:08 -0400 From: Richard Yao User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130522 Thunderbird/17.0.6 MIME-Version: 1.0 To: gentoo-dev@lists.gentoo.org CC: Sergei Trofimovich , Kernel development list , kernel@gentoo.org, gentooligan@gmail.com Subject: Re: [gentoo-dev] dm-crypt reordering BIOs across barriers? References: <51B2A955.4010906@gentoo.org> <20130608091114.441c5f17@sf> In-Reply-To: <20130608091114.441c5f17@sf> X-Enigmail-Version: 1.6a1pre Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="----enig2DXMRNMLHKVXDLBPEOFES" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2663 Lines: 65 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2DXMRNMLHKVXDLBPEOFES Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 06/08/2013 02:11 AM, Sergei Trofimovich wrote: > On Fri, 07 Jun 2013 23:47:33 -0400 > Richard Yao wrote: >=20 >> When you use dm-crypt, block IO requests to a dm-* device will invoke >> dm_request_fn() -> map_request() -> crypt_map(). If a BIO is a write >> barrier, crypt_map() will return DM_MAPIO_REMAPPED to map_request(), >> which will immediately queue it to the device. >> >> If a few dozen IOs are queued in rapid succession with multiple write >> barriers, all write barriers will be executed before any actual write >> BIOs occur because the write IOs will be processed asynchronously in a= >> work queue. Since the barriers will be long gone by the time the write= >> IOs are queued, they can be queued in any order. >> >> Am I misunderstanding this or is dm-crypt ignoring proper write barrie= r >> semantics? >> > http://www.saout.de/pipermail/dm-crypt/2012-April/002441.html > http://lwn.net/Articles/400541/ >=20 It might be worth stating that I thought flush was a synonym for barrier. It still looks like there is an issue, despite my incorrect terminology. ------enig2DXMRNMLHKVXDLBPEOFES Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJRsvacAAoJECDuEZm+6Exk9q8P/1RtjD9/vqXi5+y+m08gt2Wu Kav5QBNpltNgo2trSLlr+HMyO0+Wv2Ibjnde1/AoNhJhIHcG2MHKObUfX3KykVwN lDn5YZynujLxJSMCqkYG16WTuvt+SkimbBNnZQyXWmtk3IxHqjFBSArxcuR5+YhH Ctl1wQHQXnLjtGmoXlGsD5Lz7GJsGNiMfoMqqYFeAsNL9nd/LjtvzxOeC81QYXBA HZbK/9UXxsBxrxdY8LtPHFn/eYA3DjmPXeGy9S4OLwsxnIHX7JbpOMzLsIWZUSbo 4BJV1q+YrdI6y4YyZTv/kNrJ7p+60desmYy2oc+Fd1MbMqkIT3S20gjt5KdczsUx uxmpbyovVSqV3tesqTMTYSaGu/6wkKXsljNx4+9+3+/RMeJ4s5aIXw2u6DaftUhT RGXYcIdBgSGRCIMq4uzIq+GRtEF5q8Cy3kGPfNe2mj568Qs7Uzr156wzqGu6zG+K IKg+LhwRpYSPV2K9LIuzfiemzvimBRrgu8HnNdIaCaqDubdyiujtiRIwFT/QLH/c 0Q/sT6qrDXqTDQAXkeMdI/Cwxc/2KfETUSv+P624eHRd7HCuu4CpISmMy8WG46e3 bM3DMgQQeGW4D4Rk58iCNuPjqzOLpk8scjFmhUJtwyjclF+ebJhbNGVgd8ET8/ff ZYtnIgHusUQ/9XgzLkYA =4E3r -----END PGP SIGNATURE----- ------enig2DXMRNMLHKVXDLBPEOFES-- -- 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/