From: Akira Fujita Subject: Re: Segmentation fault in e4defrag -c Date: Wed, 01 Jul 2009 08:43:14 +0900 Message-ID: <4A4AA312.8000007@rs.jp.nec.com> References: <20090625105558.GA21773@uio.no> <4A4487B0.9080000@sx.jp.nec.com> <20090626093816.GA3175@uio.no> <4A485929.7010403@rs.jp.nec.com> <20090629214959.GT3570@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: "Steinar H. Gunderson" , Kazuya Mio , linux-ext4@vger.kernel.org To: Andreas Dilger Return-path: Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:56953 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214AbZF3Xn6 (ORCPT ); Tue, 30 Jun 2009 19:43:58 -0400 In-Reply-To: <20090629214959.GT3570@webber.adilger.int> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi, Andreas Dilger wrote: > On Jun 29, 2009 15:03 +0900, Akira Fujita wrote: >>> Size: 4050385 Blocks: 0 IO Block: 4096 regular file >>> Device: fd12h/64786d Inode: 688755 Links: 1 >>> Access: (0644/-rw-r--r--) Uid: ( 1000/ sesse) Gid: ( 1000/ sesse) >>> Access: 2009-05-30 03:08:38.724454316 +0200 >>> Modify: 2008-09-01 20:38:26.135589449 +0200 >>> Change: 2008-09-01 20:38:26.135589449 +0200 >> File size is "4050385" but Blocks is "0" >> probably means blocks are not allocated yet or file is *corrupted*. >> Is your mp3 file available? > > Well, this is a sparse file for some reason (e.g. failed mp3 p2p download). > Ah, may be so. >> Anyway, with this patch, 0 blocks file is skipped, >> therefore the segmentation fault you had will not happen. > > Is it possible that the code has not been tested with sparse files? > In that case, the check for size == 0 is only going to catch a single > case of problem, and not handle general sparse files. > I have tested files that have sparse blocks (e.g. files that have sparse blocks in its beginning, middle and those combinations) and got fine results. Unfortunately, like this case, only 0 blocks file (all sparse blocks) has not been tested yet. But the kernel space (EXT4_IOC_MOVE_EXTENT) does not have this kind of issue. Because there is a check of whether the extents of orig_inode that ext4_ext_find_extent() gets is NULL. If extents is NULL or ext4_ext_find_extent() fails, ext4_move_extents() returns an error value (e.g. EINVAL) to the user space. Regards, Akira Fujita