From: Andreas Dilger Subject: Re: [PATCH 1/2] ext4: journal all modifications in ext4_xattr_set_handle Date: Sat, 07 Nov 2009 12:22:13 -0700 Message-ID: <5103C29A-FE60-4AA7-8D41-30C21D2CC84E@sun.com> References: <4AF4A334.1000304@redhat.com> <4AF4A49F.8030005@redhat.com> <55C0D494-12AD-4EF7-8C35-411B2B5151EF@sun.com> <20091107023341.GF26342@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7BIT Cc: Eric Sandeen , ext4 development To: Theodore Tso Return-path: Received: from sca-es-mail-2.Sun.COM ([192.18.43.133]:43389 "EHLO sca-es-mail-2.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752673AbZKGTWK (ORCPT ); Sat, 7 Nov 2009 14:22:10 -0500 Received: from fe-sfbay-10.sun.com ([192.18.43.129]) by sca-es-mail-2.sun.com (8.13.7+Sun/8.12.9) with ESMTP id nA7JMF0V004146 for ; Sat, 7 Nov 2009 11:22:15 -0800 (PST) Received: from conversion-daemon.fe-sfbay-10.sun.com by fe-sfbay-10.sun.com (Sun Java(tm) System Messaging Server 7u2-7.04 64bit (built Jul 2 2009)) id <0KSR00G006ROJD00@fe-sfbay-10.sun.com> for linux-ext4@vger.kernel.org; Sat, 07 Nov 2009 11:22:15 -0800 (PST) In-reply-to: <20091107023341.GF26342@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2009-11-06, at 19:33, Theodore Tso wrote: > On Fri, Nov 06, 2009 at 05:22:51PM -0700, Andreas Dilger wrote: >> On 2009-11-06, at 15:35, Eric Sandeen wrote: >>> Oh, and for those who haven't been following the bug, big >>> thanks to Chris Mason for helping to look into this and coming >>> up with the debugging patch that made it obvious... >> >> It would be great, IMHO, to have this debugging patch submitted to >> the kernel also, and enabled under a CONFIG option. > > The debugging patch is only safe when the file system's block size == > page size. I suppose we could leave a warning in Kconfig that the > debugging option is only safe to be used when all of the file systems > in the system have a 4k (or whatever the page size happens to be) > block size, but it's probably better to clean up the patch so that > it's only enabled on a mount option, and then only if the file system > block size is the same as the page size. Yes, definitely, but this covers about 90% of the filesystems in use, so I don't see it as a big limitation. >> I'd also be interested to see the "write shadow buffer to journal" >> one-line patch that was discussed in the bug. > > Which patch are you referring to? In bugzilla there was a comment from Chris: "Eric helped prove this is the case by testing a patch that always crcs and writes a stable duplicate of the metadata buffer instead of the metadata buffer itself (a one liner since the log code was already setup for this)." Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.