From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: interesting way to break ext3 using loop devices Date: Wed, 15 Nov 2006 15:36:20 +0100 Message-ID: <200611151536.21066.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org Return-path: Received: from mx1.suse.de ([195.135.220.2]:54751 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1030496AbWKOOgZ (ORCPT ); Wed, 15 Nov 2006 09:36:25 -0500 To: ext2-devel@lists.sourceforge.net Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org By mistake i found a sick way to break ext3: Create a sparse (only consisting of a large hole) loop file on a ext3 file system. losetup a loop device over it Create a ext3 file system in the loop device Mount it. Copy the "parent" file system into the mounted loop fs with cp -rv Eventually it will work on the copy of the loop file. When you Ctrl-C it the system becomes quite confused: - Syslog is flooded with IO errors - The loop fs cannot be unmounted anymore - sync gets stuck Of course this was clearly an operator error and copying a file system into itself is clearly a sick thing to do, but still it shouldn't cause symptoms like this. Perhaps it points to a deeper issue. -Andi