From: Eric Sandeen Subject: Re: fio test triggering bad data on ext4 Date: Fri, 18 Jun 2010 13:04:31 -0500 Message-ID: <4C1BB52F.6040609@redhat.com> References: <4C1B292C.2080205@fusionio.com> <4C1B7C73.505@redhat.com> <4C1B89C1.6090408@redhat.com> <4C1B8D1F.3020002@fusionio.com> <4C1B90AE.1050703@redhat.com> <4C1BADA1.5090705@fusionio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "tytso@mit.edu" , "adilger@sun.com" , "linux-ext4@vger.kernel.org" To: Jens Axboe Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761339Ab0FRSEr (ORCPT ); Fri, 18 Jun 2010 14:04:47 -0400 In-Reply-To: <4C1BADA1.5090705@fusionio.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Jens Axboe wrote: > On 2010-06-18 17:28, Eric Sandeen wrote: >> Jens Axboe wrote: >>> On 18/06/10 16.59, Eric Sandeen wrote: >>> >>>> Eric Sandeen wrote: >>>> >>>>> Jens Axboe wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> I was writing a small fio job file to do writes and read verifies on a >>>>>> device. It forks 32 processes, each writing randomly to 4 files with a >>>>>> block size between 4k and 16k. When it has written 1024 of those blocks, >>>>>> it'll verify the oldest 512 of them. Each block is checksummed for every >>>>>> 512b. It uses libaio and O_DIRECT. >>>>>> >>>>>> It works on ext2 and btrfs. I haven't run it to completion yet, but they >>>>>> survive 15-20 minutes just fine. ext4 doesn't even go a full minutes >>>>>> before this triggers: >>>>>> >>>>> Jens, can you try XFS too? Since ext3 can't do direct IO to a hole, >>>>> (and I'm not sure about btrfs in that regard), ext4 may be most similar >>>>> to xfs's behavior on the test ... wondering how it fares. >>>>> >>>>> Thanks, >>>>> -Eric >>>>> >>>> Actually mingming had a patch for direct-io.c which may be related, I'll >>>> test that out. >>>> >>> OK, I'll try XFS tonight as well. >>> >>> >>> >> I haven't been able to reproduce it on ext4 here, yet. >> >> FWIW here's the patch from mingming: >> >> When unaligned DIO writes, skip zero out the block if the buffer is marked >> unwritten. That means there is an asynconous direct IO (append or fill the hole) >> still pending. >> >> Signed-off-by: Mingming Cao >> --- >> fs/direct-io.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> Index: linux-git/fs/direct-io.c >> =================================================================== >> --- linux-git.orig/fs/direct-io.c 2010-05-07 15:42:22.855033403 -0700 >> +++ linux-git/fs/direct-io.c 2010-05-07 15:44:17.695007770 -0700 >> @@ -740,7 +740,8 @@ >> struct page *page; >> >> dio->start_zero_done = 1; >> - if (!dio->blkfactor || !buffer_new(&dio->map_bh)) >> + if (!dio->blkfactor || !buffer_new(&dio->map_bh) >> + || buffer_unwritten(&dio->map_bh)) >> return; >> >> dio_blocks_per_fs_block = 1 << dio->blkfactor; >> >> > > What is this patch against? > Applied to 2.6.32, seems to apply upstream as well. It hits dio_zero-block() -Eric