From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51296) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W9Lly-0000Vb-Tm for qemu-devel@nongnu.org; Fri, 31 Jan 2014 16:37:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W9Llq-0000Dk-85 for qemu-devel@nongnu.org; Fri, 31 Jan 2014 16:37:14 -0500 Received: from paradis.irqsave.net ([62.212.105.220]:48768) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W9Llp-0000AC-Oo for qemu-devel@nongnu.org; Fri, 31 Jan 2014 16:37:06 -0500 Date: Fri, 31 Jan 2014 22:37:01 +0100 From: =?iso-8859-1?Q?Beno=EEt?= Canet Message-ID: <20140131213700.GB3072@irqsave.net> References: <1390509099-695-1-git-send-email-benoit.canet@irqsave.net> <1390509099-695-9-git-send-email-benoit.canet@irqsave.net> <20140124132619.GF3342@dhcp-200-207.str.redhat.com> <52E26C98.1070206@redhat.com> <20140124144854.GI3342@dhcp-200-207.str.redhat.com> <52E27EAF.7020209@redhat.com> <20140127143644.GH7415@irqsave.net> <52E6AF7F.90000@redhat.com> <20140128000444.GA3085@irqsave.net> <52EC0862.90401@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <52EC0862.90401@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH V6 8/8] block: Use graph node name as reference in bdrv_file_open(). List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: =?iso-8859-1?Q?Beno=EEt?= Canet , Kevin Wolf , famz@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, stefanha@redhat.com Le Friday 31 Jan 2014 =C3=A0 21:32:34 (+0100), Max Reitz a =C3=A9crit : > On 28.01.2014 01:04, Beno=C3=AEt Canet wrote: > >Le Monday 27 Jan 2014 =C3=A0 20:11:59 (+0100), Max Reitz a =C3=A9crit = : > >>On 27.01.2014 15:36, Beno=C3=AEt Canet wrote: > >>>Le Friday 24 Jan 2014 =C3=A0 15:54:39 (+0100), Max Reitz a =C3=A9cri= t : > >>>>On 24.01.2014 15:48, Kevin Wolf wrote: > >>>>>Am 24.01.2014 um 14:37 hat Max Reitz geschrieben: > >>>>>>On 24.01.2014 14:26, Kevin Wolf wrote: > >>>>>>>Am 23.01.2014 um 21:31 hat Beno=C3=AEt Canet geschrieben: > >>>>>>>>Signed-off-by: Benoit Canet > >>>>>>>>--- > >>>>>>>> block.c | 6 +++--- > >>>>>>>> 1 file changed, 3 insertions(+), 3 deletions(-) > >>>>>>>I'm not going to merge this one yet. It breaks qemu-iotests case= 071, > >>>>>>>which would have to be adapted. > >>>>>>> > >>>>>>>However, first of all I'd like to hear the opinions of at least = Eric and > >>>>>>>Max on what BlockRef should really refer to. I think node names = make > >>>>>>>most sense, but perhaps it's a bit inconvenient and the command = line > >>>>>>>should default to node-name =3D id when id is set, but node-name= isn't? > >>>>>>The QAPI schema is pretty clear about this: =E2=80=9Creferences t= he ID of an > >>>>>>existing block device.=E2=80=9D > >>>>>Sure, that's because I wrote that text before we had a node name. > >>>>> > >>>>>However, in 1.7 references didn't work yet, so we still have all f= reedom > >>>>>to change the interface as we like. > >>>>Yes, that's right. > >>>> > >>>>>>However, if the ID cannot be found, I think > >>>>>>we should interpret it as a reference to the node name. > >>>>>> > >>>>>>Therefore, I'd first try bdrv_find() and if that returns NULL, tr= y > >>>>>>again with bdrv_find_node(). > >>>>>I think I would prefer to avoid such ambiguities. Otherwise a mana= gement > >>>>>tool that wants to use the node name needs to check first if it's = not > >>>>>already used as a device name somewhere else and would therefore o= perate > >>>>>on the wrong device. > >>>>> > >>>>>On the other hand, a management tool using the same names for devi= ces > >>>>>and nodes just gets what it deserves. > >>>>> > >>>>>Perhaps we should use a common namespace for both, i.e. you get an= error > >>>>>if you try to assign a node name that is already a device name and= vice > >>>>>versa? > >>>>This is what I would go for. However, then I don't really know why > >>>>we should separate the ID and the node name in the first place > >>>>(although that's probably because I haven't followed the discussion > >>>>around node names). > >>>> > >>>>Max > >>>Ping, > >>> > >>>I still want to make quorum merge. > >>>What should be done for the references ? > >>> > >>>Best regards > >>> > >>>Beno=C3=AEt > >>My only problem is that I don't really know what IDs are for, then. ;= -) > >> > > From the understanding I have ID are for block backend top level bds = and > >node-name naming all the bds burried in the graph. > > > >So my personal opinion would be to relax the constraint on bdrv_lookup= _bs > >and use it for references. > > > >Kevin && Max: what do you think of this scheme ? >=20 > I agree. For example, we could change the constraint to report an > error only if both ID and node name are actually valid (and point to > different devices), that is, bdrv_find() and bdrv_find_node() return > different non-NULL values. Ok I will write patch doing this on top of quorum patches. Best regards Beno=C3=AEt >=20 > Max