From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 03/12] ext4: Remove bogus wait for unwritten extents in ext4_ind_direct_IO Date: Tue, 22 Jan 2013 14:44:00 +0100 Message-ID: <20130122134400.GB28331@quack.suse.cz> References: <1358510446-19174-1-git-send-email-jack@suse.cz> <1358510446-19174-4-git-send-email-jack@suse.cz> <87k3r5qxpf.fsf@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Ted Tso , linux-ext4@vger.kernel.org To: Dmitry Monakhov Return-path: Received: from cantor2.suse.de ([195.135.220.15]:50458 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751764Ab3AVNoD (ORCPT ); Tue, 22 Jan 2013 08:44:03 -0500 Content-Disposition: inline In-Reply-To: <87k3r5qxpf.fsf@openvz.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue 22-01-13 15:11:24, Dmitry Monakhov wrote: > On Fri, 18 Jan 2013 13:00:37 +0100, Jan Kara wrote: > > When using indirect blocks there is no possibility to have any unwritten > > extents. So wait for them in ext4_ind_direct_IO() is just bogus. > But as soon as i remember indirect implementation may also be used by > extents based inodes 3074: ext4_ext_direct_IO > /* Use the old path for reads and writes beyond i_size. */ > if (rw != WRITE || final_size > inode->i_size) > return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); > > Am I missing ? Ah, that's a catch. Thanks for pointing that out! So my patch is wrong and that code path needs some cleaning and commenting. In particular I'm afraid using dioread_nolock for inodes with indirect map causes data exposure bugs when unlocked DIO read races with DIO write because such inodes don't support uninitialized extents. Honza -- Jan Kara SUSE Labs, CR