From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:59287)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <famz@redhat.com>) id 1Z2c3J-000563-Iu
	for qemu-devel@nongnu.org; Wed, 10 Jun 2015 05:12:06 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <famz@redhat.com>) id 1Z2c3I-0005hO-KI
	for qemu-devel@nongnu.org; Wed, 10 Jun 2015 05:12:05 -0400
Date: Wed, 10 Jun 2015 17:11:56 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20150610091156.GA11648@ad.nay.redhat.com>
References: <1433759662-25139-1-git-send-email-famz@redhat.com>
	<1433759662-25139-2-git-send-email-famz@redhat.com>
	<5575A402.3040301@redhat.com> <5575AC85.7020101@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5575AC85.7020101@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 1/3] block: Extrace
 bdrv_parse_detect_zeroes_flags
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, Jeff Cody <jcody@redhat.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>, stefanha@redhat.com

On Mon, 06/08 16:53, Paolo Bonzini wrote:
> 
> 
> On 08/06/2015 16:17, Eric Blake wrote:
> >> > +
> >> > +    if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
> >> > +        !(bdrv_flags & BDRV_O_UNMAP)) {
> >> > +        error_setg(errp, "setting detect-zeroes to unmap is not allowed "
> >> > +                         "without setting discard operation to unmap");
> >> > +    }
> > I think it might be better to have a tri-state enum, than to have two
> > competing bools where only 3 of the 4 states are valid.
> 
> Note that this is not a bool.  We have one bool and one 3-element enum
> (off/on/unmap), where only 5 of the 6 states are valid.  Also, at least
> detect-zeroes would go away if we had some kind of blockdev-mirror
> (where the target is added first with blockdev-add), so I think it's
> better to leave it separate.

Agreed. But by then "drive-mirror derive=... detect-zeroes=unmap unmap=false"
will be way too confusing.

I say let's save that and just go for blockdev-add :)

https://www.mail-archive.com/qemu-devel@nongnu.org/msg301990.html

Fam