From: Alex Bligh <alex@alex.org.uk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Alex Bligh <alex@alex.org.uk>, Wouter Verhelst <w@uter.be>,
"nbd-general@lists.sourceforge.net"
<nbd-general@lists.sourceforge.net>, Josef Bacik <jbacik@fb.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-block@vger.kernel.org, Markus Pargmann <mpa@pengutronix.de>,
kernel-team@fb.com
Subject: Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements
Date: Thu, 15 Sep 2016 12:43:35 +0100 [thread overview]
Message-ID: <751994A2-653B-4201-8210-A31495804788@alex.org.uk> (raw)
In-Reply-To: <20160915113807.GA23259@infradead.org>
Christoph,
> On 15 Sep 2016, at 12:38, Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Sep 15, 2016 at 12:49:35PM +0200, Wouter Verhelst wrote:
>> A while back, we spent quite some time defining the semantics of the
>> various commands in the face of the NBD_CMD_FLUSH and NBD_CMD_FLAG_FUA
>> write barriers. At the time, we decided that it would be unreasonable
>> to expect servers to make these write barriers effective across
>> different connections.
>
> Do you have a nbd protocol specification? treating a flush or fua
> as any sort of barrier is incredibly stupid. Is it really documented
> that way, and if yes, why?
Sure, it's at:
https://github.com/yoe/nbd/blob/master/doc/proto.md#ordering-of-messages-and-writes
and that link takes you to the specific section.
The treatment of FLUSH and FUA is meant to mirror exactly the
linux block layer (or rather how the linux block layer was a few
years ago). I even asked on LKML to verify a few points.
--
Alex Bligh
next prev parent reply other threads:[~2016-09-15 11:43 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-08 21:12 [RESEND][PATCH 0/5] nbd improvements Josef Bacik
2016-09-08 21:12 ` [PATCH 1/5] nbd: convert to blkmq Josef Bacik
2016-09-08 21:12 ` [PATCH 2/5] nbd: don't shutdown sock with irq's disabled Josef Bacik
2016-09-08 21:12 ` [PATCH 3/5] nbd: use flags instead of bool Josef Bacik
2016-09-09 1:20 ` Joe Perches
2016-09-09 13:55 ` Jens Axboe
2016-09-09 16:04 ` Joe Perches
2016-09-09 16:11 ` Jens Axboe
2016-09-09 16:15 ` Joe Perches
2016-09-09 16:20 ` Jens Axboe
2016-09-08 21:12 ` [PATCH 4/5] nbd: allow block mq to deal with timeouts Josef Bacik
2016-09-08 21:12 ` [PATCH 5/5] nbd: add multi-connection support Josef Bacik
2016-09-10 7:43 ` Christoph Hellwig
2016-09-12 13:11 ` Josef Bacik
2016-09-09 20:02 ` [Nbd] [RESEND][PATCH 0/5] nbd improvements Wouter Verhelst
2016-09-09 20:36 ` Josef Bacik
2016-09-09 20:55 ` Wouter Verhelst
2016-09-09 23:00 ` Josef Bacik
2016-09-09 23:37 ` Jens Axboe
2016-09-15 10:49 ` Wouter Verhelst
2016-09-15 11:09 ` Alex Bligh
2016-09-15 11:29 ` Wouter Verhelst
2016-09-15 11:40 ` Christoph Hellwig
2016-09-15 11:46 ` Alex Bligh
2016-09-15 11:52 ` Christoph Hellwig
2016-09-15 12:01 ` Wouter Verhelst
2016-09-15 12:20 ` Christoph Hellwig
2016-09-15 12:26 ` Wouter Verhelst
2016-09-15 12:27 ` Christoph Hellwig
2016-09-15 12:04 ` Alex Bligh
2016-09-15 11:39 ` Christoph Hellwig
2016-09-15 13:34 ` Eric Blake
2016-09-15 14:07 ` Paolo Bonzini
2016-09-15 15:23 ` Alex Bligh
2016-09-15 21:10 ` Paolo Bonzini
2016-09-15 15:25 ` Alex Bligh
2016-09-15 11:38 ` Christoph Hellwig
2016-09-15 11:43 ` Alex Bligh [this message]
2016-09-15 11:46 ` Christoph Hellwig
2016-09-15 11:56 ` Alex Bligh
2016-09-15 11:55 ` Wouter Verhelst
2016-09-15 12:01 ` Christoph Hellwig
2016-09-15 12:11 ` Alex Bligh
2016-09-15 12:18 ` Christoph Hellwig
2016-09-15 12:28 ` Alex Bligh
2016-09-15 12:21 ` Wouter Verhelst
2016-09-15 12:23 ` Christoph Hellwig
2016-09-15 12:33 ` Alex Bligh
2016-09-15 12:36 ` Christoph Hellwig
2016-09-15 12:39 ` Alex Bligh
2016-09-15 12:41 ` Christoph Hellwig
2016-09-15 12:44 ` Alex Bligh
2016-09-15 13:17 ` Wouter Verhelst
2016-09-15 13:57 ` Josef Bacik
2016-09-15 15:17 ` Alex Bligh
2016-09-15 16:08 ` Alex Bligh
2016-09-15 16:27 ` Wouter Verhelst
2016-09-15 16:42 ` Alex Bligh
2016-09-15 19:02 ` Eric Blake
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