From: Theodore Tso Subject: Re: [PATCH 05/11] ext4: Make sure blocks are properly allocated under mmaped page even when blocksize < pagesize Date: Wed, 27 May 2009 10:30:06 -0400 Message-ID: <20090527143006.GC10842@mit.edu> References: <1243429268-3028-1-git-send-email-jack@suse.cz> <1243429268-3028-6-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: LKML , npiggin@suse.de, linux-ext4@vger.kernel.org, "Aneesh Kumar K.V" To: Jan Kara Return-path: Received: from THUNK.ORG ([69.25.196.29]:36784 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758598AbZE0OaP (ORCPT ); Wed, 27 May 2009 10:30:15 -0400 Content-Disposition: inline In-Reply-To: <1243429268-3028-6-git-send-email-jack@suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, May 27, 2009 at 03:01:02PM +0200, Jan Kara wrote: > In a situation like: > truncate(f, 1024); > a = mmap(f, 0, 4096); > a[0] = 'a'; > truncate(f, 4096); > > we end up with a dirty page which does not have all blocks allocated / > reserved. Fix the problem by using new VFS infrastructure. > > Signed-off-by: Jan Kara Hi Jan, Have you tested with -o nodelalloc? There is apparently a problem with ext4 when blocksize < pagesize which Aneesh has been working on. He has been able to reproduce the problem, and theorized that an earlier version your patch set would address the problem, but it apparently did not. See: http://bugzilla.kernel.org/show_bug.cgi?id=13369 ... and Aneesh can provide more details. Aneesh, you might want to try testing with this latest set and see if you can reproduce the problem with this set. - Ted