From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:39940 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752200Ab3H2QLz (ORCPT ); Thu, 29 Aug 2013 12:11:55 -0400 Message-ID: <521F72C6.3040600@redhat.com> Date: Thu, 29 Aug 2013 11:11:50 -0500 From: Eric Sandeen MIME-Version: 1.0 To: Hidetoshi Seto CC: linux-btrfs@vger.kernel.org, chris.mason@fusionio.com Subject: Re: [PATCH 0/2] btrfs-progs: prevent mkfs from aborting with small volume References: <52170114.7060604@jp.fujitsu.com> <521B64EA.2080106@redhat.com> <521D842D.6020100@jp.fujitsu.com> In-Reply-To: <521D842D.6020100@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-2022-JP Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 8/28/13 12:01 AM, Hidetoshi Seto wrote: > (2013/08/26 23:23), Eric Sandeen wrote: >> Thanks for looking into this - how small of a device did you test? >> >> I tried a 2MB device w/ these 2 patches and still got: >> >> [btrfs-progs]# truncate --size=2m testfile >> [btrfs-progs]# ./mkfs.btrfs testfile >> >> WARNING! - Btrfs v0.20-rc1-360-geeeb4e9 IS EXPERIMENTAL >> WARNING! - see http://btrfs.wiki.kernel.org before using >> >> SMALL VOLUME: forcing mixed metadata/data groups >> mkfs.btrfs: volumes.c:857: btrfs_alloc_chunk: Assertion `!(ret)' failed. >> Aborted (core dumped) >> >> which was at: >> >> ret = btrfs_alloc_dev_extent(trans, device, >> info->chunk_root->root_key.objectid, >> BTRFS_FIRST_CHUNK_TREE_OBJECTID, key.offset, >> calc_size, &dev_offset); >> BUG_ON(ret); >> >> :( > > Wow... > It seems that this abort is different problem from the bug which > my patches are going to fix. I'll try to make new patch to fix this > problem. > >> >> Also, I'm curious - I know the code existed before your patch 2/2, >> but I don't understand why it reserves 1MB for the first superblock >> when the first superblock is actually at 64k. Any idea? >> >> -Eric > > I'm not sure... According to the git-log, this 1M trick is in > the following old commit by Chris: > > commit a6de0bd778475504f42a142c83b8077993cbddfe > Author: Chris Mason > Date: Thu Apr 3 16:35:48 2008 -0400 > > Add mirroring support across multiple drives Yep I saw that too. Seemingly unrelated. :( Unless I'm missing something (which I probably am). -Eric > > Thanks, > H.Seto >