From: Subject: RE: Re: jbd2 inside a device mapper module Date: Mon, 29 Dec 2008 11:50:14 +0530 Message-ID: <46A00B48CC54E4468EF6911F877AC4CA01DDBB66@blrx3m10.blr.amer.dell.com> References: <20081224211038.GT4127@blitiri.com.ar><20081224234915.GA23723@mit.edu> <20081225143535.GA4127@blitiri.com.ar> <20081227200127.GX5000@webber.adilger.int> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0093007039==" Cc: linux-ext4@vger.kernel.org, tytso@MIT.EDU, linux-kernel@vger.kernel.org To: , , Return-path: Content-class: urn:content-classes:message In-Reply-To: <20081227200127.GX5000@webber.adilger.int> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com List-Id: linux-ext4.vger.kernel.org This is a multi-part message in MIME format. --===============0093007039== Content-class: urn:content-classes:message Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C9697D.834D0253" This is a multi-part message in MIME format. ------_=_NextPart_001_01C9697D.834D0253 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Andreas Dilger wrote: > On Dec 25, 2008 12:35 -0200, Alberto Bertogli wrote: > > On Wed, Dec 24, 2008 at 06:49:15PM -0500, Theodore Tso wrote: > > > I have no idea why you would need to do manual __breads(). No doubt > > > I'm missing some context here. =20 > > > > I'm writing (just for fun and learning purposes) a device mapper > > module that stores checksums on writes and verifies them on reads. The > > integrity metadata (currently just the checksum) is interleaved in the > > backing device: one sector holding the integrity metadata for the > > following 64 data sectors. > Alex and I discussed implementing checksums for ext4 using an external device like this, and he might have some more design information for you. That external device could possibly be a TPM chip that can store checksums. Shyam Iyer Dell Linux Engineering ------_=_NextPart_001_01C9697D.834D0253 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Andreas Dilger wrote:
> On Dec 25, 2008  = 12:35 -0200,=20 Alberto Bertogli wrote:
> > On Wed, Dec 24, 2008 at 06:49:15PM = -0500,=20 Theodore Tso wrote:
> > > I have no idea why you would need = to do=20 manual __breads().  No doubt
> > > I'm missing some = context=20 here.  
> >
> > I'm writing (just for fun = and=20 learning purposes) a device mapper
> > module that stores = checksums on=20 writes and verifies them on reads. The
> > integrity metadata=20 (currently just the checksum) is interleaved in the
> > backing = device:=20 one sector holding the integrity metadata for the
> > following = 64 data=20 sectors.

> Alex and I discussed implementing checksums for = ext4 using=20 an external device like this, and he might have some more design = information for=20 you.

That = external device=20 could possibly be a TPM chip that can store=20 checksums.

Shyam = Iyer
Dell Linux = Engineering
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