From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 18 Dec 2006 22:32:23 -0800 (PST) Received: from relay.sw.ru (mailhub.sw.ru [195.214.233.200]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id kBJ6WGqw028254 for ; Mon, 18 Dec 2006 22:32:18 -0800 Subject: Re: [PATCH] incorrect direct io error handling References: <000101c722de$9fdca4b0$e834030a@amr.corp.intel.com> From: Dmitriy Monakhov Date: Tue, 19 Dec 2006 09:31:15 +0300 In-Reply-To: <000101c722de$9fdca4b0$e834030a@amr.corp.intel.com> (Kenneth W. Chen's message of "Mon, 18 Dec 2006 11:56:36 -0800") Message-ID: <87lkl4tn0s.fsf@sw.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: "Chen, Kenneth W" Cc: 'Dmitriy Monakhov' , linux-kernel@vger.kernel.org, devel@openvz.org, Andrew Morton , xfs@oss.sgi.com "Chen, Kenneth W" writes: > Dmitriy Monakhov wrote on Monday, December 18, 2006 5:23 AM >> This patch is result of discussion started week ago here: >> http://lkml.org/lkml/2006/12/11/66 >> changes from original patch: >> - Update wrong comments about i_mutex locking. >> - Add BUG_ON(!mutex_is_locked(..)) for non blkdev. >> - vmtruncate call only for non blockdev >> LOG: >> If generic_file_direct_write() has fail (ENOSPC condition) inside >> __generic_file_aio_write_nolock() it may have instantiated >> a few blocks outside i_size. And fsck will complain about wrong i_size >> (ext2, ext3 and reiserfs interpret i_size and biggest block difference as error), >> after fsck will fix error i_size will be increased to the biggest block, >> but this blocks contain gurbage from previous write attempt, this is not >> information leak, but its silence file data corruption. This issue affect >> fs regardless the values of blocksize or pagesize. >> We need truncate any block beyond i_size after write have failed , do in simular >> generic_file_buffered_write() error path. If host is !S_ISBLK i_mutex always >> held inside generic_file_aio_write_nolock() and we may safely call vmtruncate(). >> Some fs (XFS at least) may directly call generic_file_direct_write()with >> i_mutex not held. There is no general scenario in this case. This fs have to >> handle generic_file_direct_write() error by its own specific way (place). > > > I'm puzzled that if ext2 is able to instantiate some blocks, then why does it > return no space error? Where is the error coming from? generic_file_aio_write_nolock() ->generic_file_direct_write() ->generic_file_direct_IO() ->ext2_direct_IO(WRITE,...) ->blockdev_direct_IO( ....,ext2_get_block,...)