From owner-freebsd-stable@FreeBSD.ORG Thu Dec 4 07:31:04 2008 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 96C661065676; Thu, 4 Dec 2008 07:31:04 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from out1.smtp.messagingengine.com (out1.smtp.messagingengine.com [66.111.4.25]) by mx1.freebsd.org (Postfix) with ESMTP id 666D38FC13; Thu, 4 Dec 2008 07:31:04 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from compute2.internal (compute2.internal [10.202.2.42]) by out1.messagingengine.com (Postfix) with ESMTP id D38451CCF09; Thu, 4 Dec 2008 02:15:07 -0500 (EST) Received: from heartbeat2.messagingengine.com ([10.202.2.161]) by compute2.internal (MEProxy); Thu, 04 Dec 2008 02:15:07 -0500 X-Sasl-enc: EQDauYBCrxW/pU5OuZOqHdtKdL86qR9yYZfh2Ygwt3vM 1228374907 Received: from empiric.lon.incunabulum.net (82-35-112-254.cable.ubr07.dals.blueyonder.co.uk [82.35.112.254]) by mail.messagingengine.com (Postfix) with ESMTPSA id 1BD5F24DF8; Thu, 4 Dec 2008 02:15:07 -0500 (EST) Message-ID: <49378379.5050900@FreeBSD.org> Date: Thu, 04 Dec 2008 07:15:05 +0000 From: "Bruce M. Simpson" User-Agent: Thunderbird 2.0.0.14 (X11/20080514) MIME-Version: 1.0 To: Kostik Belousov References: <8cb6106e0811241129o642dcf28re4ae177c8ccbaa25@mail.gmail.com> <20081125140601.GH2042@deviant.kiev.zoral.com.ua> <8cb6106e0811250617q5fffb41exe20dfb8314fc4a9d@mail.gmail.com> <20081125142827.GI2042@deviant.kiev.zoral.com.ua> <8cb6106e0811250657q6fdf08b0x1e94f35fd0a7ed4f@mail.gmail.com> <20081125150342.GL2042@deviant.kiev.zoral.com.ua> <8cb6106e0812031453j6dc2f2f4i374145823c084eaa@mail.gmail.com> In-Reply-To: <8cb6106e0812031453j6dc2f2f4i374145823c084eaa@mail.gmail.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: josh.carroll@gmail.com, freebsd-fs@freebsd.org, FreeBSD Stable Subject: Re: ext2 inode size patch - RE: PR kern/124621 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Dec 2008 07:31:04 -0000 Hi, The inode size for the ext3 filesystem which Gentoo created for my last install defaulted to 256 bytes, so I got bit by this problem. I can't speak for the write path. but the read path looks just fine to me, and the patch should go in ASAP. Josh Carroll wrote: >> Ok, I describe my concern once more. I do not object against the checking >> of the inode size. But, if inode size is changed, then some data is added >> to the inode, that could (and usually does, otherwise why extend it ?) >> change intrerpetation of the inode. Thus, we need a verification of the >> fact that simply ignoring added fields does not damage filesystem or >> cause user data corruption. Verification != testing. >> If folk are paranoid, then add a check for dynamic inode size and disable ext2fs writes by downgrading the mount in that case (We can do that, right? Can someone make sure Josh gets the help he needs here?) As Josh points out, the ext2 inode size is stored in the superblock. Whilst it may vary between ext2 filesystems, *the inode size itself does not appear to be something which one can modify in an existing ext2/3 filesystem*. Older ext2 filesystems may not contain the inode size field in the superblock, and the patch appears to default to 128 for that case. The double indirection thus introduced doesn't concern me, our ext2fs is not performance critical code, and the superblock is likely to sit in L2/L3 cache anyway (note: content free argument). Thanks to Josh for fixing this problem. cheers BMS