From: Paul Clements <paul.clements@us.sios.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] [RESEND] add discard support to nbd
Date: Fri, 31 Aug 2012 11:24:31 -0400 [thread overview]
Message-ID: <CAECXXi7viVEV9eeZ-LvE-wRTDe_r76=1iWffMNPeG1c-Gx5=bA@mail.gmail.com> (raw)
In-Reply-To: <20120830150348.287bfa2f.akpm@linux-foundation.org>
On Thu, Aug 30, 2012 at 6:03 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Wed, 29 Aug 2012 08:41:02 -0400
> paul.clements@steeleye.com wrote:
>
>> Description: This patch adds discard support to nbd. When the nbd client
>> system receives a discard request, this will be passed along to the nbd
>> server system, where the nbd-server will respond by performing:
>> fallocate(.. FALLOC_FL_PUNCH_HOLE ..)
>>
>> To punch a hole in the backend storage, which is no longer needed.
>>
>
> What happens if the user is running an older server?
In that case, the older server will not have set NBD_SEND_FLAG_TRIM,
so QUEUE_FLAG_DISCARD doesn't get set, so no discards will be sent to
the device.
> I is it possible that because the old server didn't set
> NBD_FLAG_SEND_TRIM, the user's screen gets filled with WARN_ONs?
No.
> Anyway, please make sure this combination was tested!
It was.
Thanks for the feedback.
I will resend v2 of the patches shortly.
--
Paul
prev parent reply other threads:[~2012-08-31 15:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-29 12:41 [PATCH 2/2] [RESEND] add discard support to nbd paul.clements
2012-08-30 22:03 ` Andrew Morton
2012-08-31 15:24 ` Paul Clements [this message]
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