From: Theodore Ts'o Subject: Re: EXT4 regression caused 4eec7 Date: Mon, 13 May 2013 09:30:36 -0400 Message-ID: <20130513133036.GB4845@thunk.org> References: <31302271.2821368363898561.JavaMail.weblogic@epml17> <20130513131809.GG400@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: EUNBONG SONG , Dmitry Monakhov , "linux-ext4@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-xfs@vger.kernel.org" , Dave Chinner To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20130513131809.GG400@quack.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, May 13, 2013 at 03:18:09PM +0200, Jan Kara wrote: > Grumble. In this case I think bitfields are not worth the trouble with gcc. > It's a pitty we have to spend additional 8 bytes for every journal_head but > we'll survive... I'll send Ted a partial revert and add a comment so that > we won't repeat this mistake in future. Or just switch things to use explicit 32-bit boolean operations. Sounds the safest way to go is to simply not trust bitfields to be something gcc is competent to compile correctly, and just open code it in standard C. (Large portions of ext4 and e2fsprogs do this manually, for historical reasons, and it sounds like we have a good reason to do it going forward.) Jan, Dmitry --- I still have in my tree a revert for commit 4eec708d2: ext4: use io_end for multiple bios, since I belive Dmitry still bisected a regression for xfstests 299. Dmitry, can you confirm that you are definitely seeing a regression here? Jan, do you mind if we try to figure out how to fix this during the next development cycle, since it was part of your much longer, extensive patch series anyway? I've determined that the reason why I didn't see a problem was because xfstests 299 was failing earlier on the baseline, and crashing my regression tests. So I simply commented it out just so I could complete the testing. It seems that xfstests 299 is problematic for me, and I need to focus on how to make it pass successfully. (Dmitry, when I revert the commit which you identified, xfstests 299 is *still* failing for me....) - Ted