Date: Tue, 7 Jan 2014 13:59:54 -0800
From: Kent Overstreet <kmo@daterainc.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-bcache@vger.kernel.org, Neil Brown <neilb@suse.de>,
        Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] bcache/md: Use raid stripe size
Message-ID: <20140107215954.GL9037@kmo>
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On Mon, Jan 06, 2014 at 09:04:25PM -0500, Mike Snitzer wrote:
> On Wed, Dec 18, 2013 at 8:12 PM, Kent Overstreet <kmo@daterainc.com> wrote:
> > Now that we've got code for raid5/6 stripe awareness, bcache just needs
> > to know about the stripes and when writing partial stripes is expensive
> > - we probably don't want to enable this optimization for raid1 or 10,
> > even though they have stripes. So add a flag to queue_limits.
> >
> > Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> > ---
> > This is in my pile of bcache stuff queued up for 3.14 - if no one objects it'll
> > be in my bcache pull request:
> >
> >  drivers/md/bcache/super.c | 6 ++++++
> >  drivers/md/raid5.c        | 1 +
> >  include/linux/blkdev.h    | 1 +
> >  3 files changed, 8 insertions(+)
> 
> Hi Kent,
> 
> > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> > index 02cb6f0ea7..0375654adb 100644
> > --- a/include/linux/blkdev.h
> > +++ b/include/linux/blkdev.h
> > @@ -291,6 +291,7 @@ struct queue_limits {
> >         unsigned char           discard_misaligned;
> >         unsigned char           cluster;
> >         unsigned char           discard_zeroes_data;
> > +       unsigned char           raid_partial_stripes_expensive;
> >  };
> >
> >  struct request_queue {
> 
> If you add a new member to queue_limits you need to update
> blk_stack_limits() so that it propagates as you stack devices.

Thanks, going to send Jens a new pull after he does some merging so I'll include
that in the updated version.
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