lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20130313084318.GA11553@gmail.com> Date: Wed, 13 Mar 2013 16:43:18 +0800 From: Zheng Liu <gnehzuil.liu@...il.com> To: Theodore Ts'o <tytso@....edu> Cc: Lukáš Czerner <lczerner@...hat.com>, Eric Whitney <enwlinux@...il.com>, linux-ext4@...r.kernel.org, Zheng Liu <wenqing.lz@...bao.com> Subject: Re: [REGRESSION] allocated N with only M reserved metadata blocks On Tue, Mar 12, 2013 at 12:19:13PM -0400, Theodore Ts'o wrote: > On Tue, Mar 12, 2013 at 03:11:23PM +0100, Lukáš Czerner wrote: > > So there is indeed a problem with the mentioned commit > > > > 67a5da564f97f31c4054d358e00b34d7ee570da5 > > > > Due to the bug in that code is has exactly the opposite result - > > with this commit we will _never_ zero out blocks instead of creating > > uninitialized extents. In other words, we will always create > > uninitialized extent. > > Whoops. I even remember how this bug happened. Originally > max_zeroout was in file system blocks, and it was suggested that we > change this to use units of kilobytes instead. Unfortunately, this > change wasn't done completely. :-( > > > This can be easily fixed by the following patch (which makes the > > warning go away), but it brings up a question whether this "optimization" > > was worth it in the first place since noone noticed that it had exactly > > the opposite effect than it should have had :) > > Well, I had noticed that random AIO workloads resulted in the extent > tree getting far more fragmented than I had expected. (See previous > discusisons about how we really need to improve our ability to merge > empty leaf and index nodes in the extent tree.) Agree, we could do better in merging extent tree. I will take a look at it, but, sorry, my plate is too full recently. So it has a low priority. Regards, - Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists