linux-kernel - Re: Mount ext3 with barrier=1 doesn't send real barrier bio?

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Date:	Fri, 22 Aug 2008 09:58:21 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc:	Eric Sandeen <sandeen@...deen.net>, Milan Broz <mbroz@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Ric Wheeler <rwheeler@...hat.com>,
	"MASON,CHRISTOPHER" <CHRIS.MASON@...cle.com>
Subject: Re: Mount ext3 with barrier=1 doesn't send real barrier bio?

On Fri, Aug 22 2008, OGAWA Hirofumi wrote:
> Jens Axboe <jens.axboe@...cle.com> writes:
> 
> >> This should be ((rw & RW_MASK) == WRITE) too?  Anyway, this seems change
> >> behavior of submit_bh(WRITE_BARRIER) (maybe reiserfs only), it wouldn't
> >> be your intent...
> >
> > Yes, I believe the simpler and more correct fix is:
> >
> > diff --git a/fs/buffer.c b/fs/buffer.c
> > index 38653e3..16b2263 100644
> > --- a/fs/buffer.c
> > +++ b/fs/buffer.c
> > @@ -2926,14 +2926,13 @@ int submit_bh(int rw, struct buffer_head * bh)
> >  	BUG_ON(!buffer_mapped(bh));
> >  	BUG_ON(!bh->b_end_io);
> >  
> > -	if (buffer_ordered(bh) && (rw == WRITE))
> > +	if (buffer_ordered(bh) && (rw & WRITE))
> >  		rw = WRITE_BARRIER;
> 
> I see. But, umm..., this means WRITE_SYNC with barrier was deprecated?
> Or typo?

It was supposed to read rw |= WRITE_BARRIER :-)

-- 
Jens Axboe

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