From: Andreas Dilger Subject: Re: [PATCH 3/3] mke2fs: prevent creation of unmountable ext4 with large flex_bg count Date: Fri, 13 Jun 2014 15:45:03 -0600 Message-ID: <4206D78A-FD6D-4F3E-8CD1-5D717784BCA8@dilger.ca> References: <28989C0C9F1C0A428470D967B5FCED372A7EA3@BPXM22GP.gisp.nec.co.jp> <6A410081-0492-4378-BA66-07AFA7C0DEAF@dilger.ca> <20140612235019.GB9743@birch.djwong.org> Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Content-Type: multipart/signed; boundary="Apple-Mail=_8F824BFD-FABD-488A-B495-8D482A6D4121"; protocol="application/pgp-signature"; micalg=pgp-sha1 Cc: Akira Fujita , Theodore Tso , Ext4 Developers List To: "Darrick J. Wong" Return-path: Received: from mail-pa0-f54.google.com ([209.85.220.54]:43076 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986AbaFMVpL (ORCPT ); Fri, 13 Jun 2014 17:45:11 -0400 Received: by mail-pa0-f54.google.com with SMTP id et14so2518218pad.41 for ; Fri, 13 Jun 2014 14:45:11 -0700 (PDT) In-Reply-To: <20140612235019.GB9743@birch.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: --Apple-Mail=_8F824BFD-FABD-488A-B495-8D482A6D4121 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Jun 12, 2014, at 5:50 PM, Darrick J. Wong = wrote: > On Wed, Jun 11, 2014 at 01:01:29PM -0600, Andreas Dilger wrote: >>=20 >> This also reminds me of my previous flex_bg patch: >> [PATCH][RFC] mke2fs: handle flex_bg collision with backup descriptors >> http://permalink.gmane.org/gmane.comp.file-systems.ext4/42298 >>=20 >> which fixes the "bmap-imap-itable-bmap-imap-itable" problem when a = large >> flex_bg size is used. Sadly, there were no comments on that patch. >=20 > I had wondered if you were planning to address the FIXMEs in the = patch, but > then forgot to ever follow up... :/ Well, I was thinking that the patch was good enough to land as-is. It = fixes 99% the problem for flex_bg size up to 65536, but only 95% of the = groups for flex_bg of 131072. I guess I'll send it out again without = [RFC], and if people start using flex_bg >=3D 131072 (which is enough = for all the metadata in a 16TB chunk) then we can work out the final = details. I suspect that the sparse_super2 feature would probably become = more prevalent and avoid this problem entirely. Cheers, Andreas --Apple-Mail=_8F824BFD-FABD-488A-B495-8D482A6D4121 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP using GPGMail -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIVAwUBU5tw33Kl2rkXzB/gAQL+ZxAAmKYvFR5hZt9AAW8Mws9Yig1secfpbqbx p7NXyzZ2XtBwkBnjwxeeujBjr6diuaew183y4qvjOY6qiFX36ZMc7UgtK/XZ/DnG GKE4JCDDIrINaQ1bCcZZoR8koBpIO/aT4yE27ojgTEc9GyXEzCDexXnkQlWFUODU iEwcZUF2tm1ZQ0+iJg1/fIBGzCQ5dcSl2T7UCkqt2GEhtThRq/B8cje3JDQZlfOB KYDrxYGLrmnF6Mudbtfy3LFtyZ0KjLlbzlvAxirnigD6ruCHHXJAIeWxDPsAHjke KFOuF+7YaFGpWDIAlpeW7eaFg5DBUP9nyKsCki+yyEKUfFP1zoBAMPkj+BOqp9dk gTIIv1QdZrMui69jlVrjo6EXsi3DxKn81XMjCquz2hTK16WS/yxK0XQkc8cvBNgk FUszoRGMWoCZJc0LJqhFq0m1TLgw5XD3HBLvAA8x8A8mJfIgT4Y2v2BDY8IM1HIx LsPG7RC7EiF0pjaKbglaESLSir328grfYylwYNw0AgHRtc4AWdOX3M4JmADwT0jK ZYp7UgIIQJ0UdWa6BhtzOtDgN0kM70NH1JG2ew5S16QqfKrEbtvL1WpGgyqZZVVN ljzdR30caqdKql06DpDKIsn0C9GQx8GywcLTBAsACDAEJYaM6Y6IYSnEk1TiFGxr wW6vow4rz/c= =k+y/ -----END PGP SIGNATURE----- --Apple-Mail=_8F824BFD-FABD-488A-B495-8D482A6D4121--