Message-ID: <48AD46C4.30207@redhat.com>
Date: Thu, 21 Aug 2008 06:43:16 -0400
From: Ric Wheeler <rwheeler@redhat.com>
Reply-To: rwheeler@redhat.com
Organization: Red Hat
User-Agent: Thunderbird 2.0.0.16 (X11/20080723)
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To: Jens Axboe <jens.axboe@oracle.com>
CC: Eric Sandeen <sandeen@sandeen.net>, Milan Broz <mbroz@redhat.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       linux-fsdevel <linux-fsdevel@vger.kernel.org>,
       "MASON,CHRISTOPHER" <CHRIS.MASON@oracle.com>
Subject: Re: Mount ext3 with barrier=1 doesn't send real barrier bio?
References: <48A5F5C6.2090204@redhat.com> <48ACAADD.2010104@sandeen.net> <20080821052604.GM20055@kernel.dk>
In-Reply-To: <20080821052604.GM20055@kernel.dk>
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Jens Axboe wrote:
> On Wed, Aug 20 2008, Eric Sandeen wrote:
>   
>> Milan Broz wrote:
>>     
>>> Hi,
>>>
>>> I run some barrier tests over device-mapper (which currently doesn't
>>> support barrier bio at all) and even if I set barrier=1 in ext3 mount,
>>> there is never any bio with barrier flag... (in 2.6.27-rc)
>>>
>>> How is the barrier=1 flag supposed to work in ext3 (JBD) now?
>>>       
>> Milan, you're right.  Ric saw this same strange behavior when doing some
>> benchmarking with and without barriers; Chris noticed the change in
>> submit_bh; I was about to write up a similar patch to what you've sent
>> already.  Jens, does Milan's fix look good to you?
>>     
>
> Yep looks good, thanks a lot Milan! I'll send in the patch, unless I'm
> badly mistaken we need it for 2.6.26-stable as well.
>
>   

I think we definitely need it there as well, thanks!

Ric

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