From: Jens Axboe <jens.axboe@oracle.com>
To: Ed Cashin <ecashin@coraid.com>
Cc: alan@lxorguk.ukuu.org.uk, akpm@linux-foundation.org,
apw@canonical.com, bonbons@linux-vserver.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] aoe: end barrier bios with EOPNOTSUPP
Date: Wed, 9 Sep 2009 22:58:35 +0200 [thread overview]
Message-ID: <20090909205835.GK18599@kernel.dk> (raw)
In-Reply-To: <30b7855d211ab5b6bef6fe2cd9b76295@coraid.com>
On Wed, Sep 09 2009, Ed Cashin wrote:
> On Wed Sep 9 13:06:42 EDT 2009, alan@lxorguk.ukuu.org.uk wrote:
> > > The bio in question is a barrier. Jens Axboe suggested that such bios
> > > need to be recognized and ended with -EOPNOTSUPP by any driver that
> > > provides its own ->make_request_fn handler and does not handle
> > > barriers.
> > >
> > > In testing the changes below eliminate the BUG.
> >
> > Presumably AoE should actually issue an ATA cache flush for this case ?
>
> Yes. The aoe driver juggles a set of in-process I/O operations that
> have been sent to the AoE target but have not yet received responses.
>
> To implement the barrier, it would stop generating new AoE write
> commands, wait for AoE write responses for all the outstanding write
> commands, issue the ATA cache flush command, wait for the response to
> the flush, and then resume normal activity.
That's how barriers work with sata to begin with, so I'd very much
recommend that you do the same in aoe instead of just not supporting it.
--
Jens Axboe
next prev parent reply other threads:[~2009-09-09 20:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200909021955.n82JtkrI032267@imap1.linux-foundation.org>
[not found] ` <20090903063539.GH12579@kernel.dk>
[not found] ` <2339aa04a4e8fb440a52624273728352@coraid.com>
[not found] ` <20090904183525.GB18599@kernel.dk>
[not found] ` <f48e25c99e41e375f2ddd85989cd39e1@coraid.com>
[not found] ` <20090905051735.GH18599@kernel.dk>
[not found] ` <366469f19c41e0150028b886f6859019@coraid.com>
[not found] ` <20090908193540.GB18599@kernel.dk>
2009-09-09 16:45 ` [PATCH] aoe: end barrier bios with EOPNOTSUPP Ed Cashin
2009-09-09 16:50 ` Ed Cashin
2009-09-09 19:03 ` Ed Cashin
2009-09-09 16:51 ` Daniel Walker
2009-09-09 17:08 ` Alan Cox
2009-09-09 18:00 ` Ed Cashin
2009-09-09 20:58 ` Jens Axboe [this message]
2009-09-09 21:23 ` Ed Cashin
2009-09-10 7:48 ` Jens Axboe
2009-09-10 15:16 ` Ed Cashin
2009-09-10 19:50 ` Jens Axboe
2009-09-10 20:03 ` Ed Cashin
2009-09-10 20:07 ` Jens Axboe
2009-09-10 20:20 ` Ed Cashin
2009-09-10 20:27 ` Ed Cashin
2009-09-10 20:29 ` Jens Axboe
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