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Mon, 9 Dec 2019 12:24:53 +0000 (UTC) Received: from EX13D32EUC004.ant.amazon.com (10.43.164.121) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 9 Dec 2019 12:24:53 +0000 Received: from EX13D32EUC003.ant.amazon.com (10.43.164.24) by EX13D32EUC004.ant.amazon.com (10.43.164.121) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 9 Dec 2019 12:24:50 +0000 Received: from EX13D32EUC003.ant.amazon.com ([10.43.164.24]) by EX13D32EUC003.ant.amazon.com ([10.43.164.24]) with mapi id 15.00.1367.000; Mon, 9 Dec 2019 12:24:49 +0000 From: "Durrant, Paul" To: =?iso-8859-1?Q?Roger_Pau_Monn=E9?= CC: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , "Konrad Rzeszutek Wilk" , Jens Axboe , Boris Ostrovsky , Juergen Gross , Stefano Stabellini Subject: RE: [PATCH 4/4] xen-blkback: support dynamic unbind/bind Thread-Topic: [PATCH 4/4] xen-blkback: support dynamic unbind/bind Thread-Index: AQHVq3SGozEa3lNeXkCoixgttFczb6exvlMAgAABmYA= Date: Mon, 9 Dec 2019 12:24:49 +0000 Message-ID: <215c57c1096548769aeaaeaa76e7c73b@EX13D32EUC003.ant.amazon.com> References: <20191205140123.3817-1-pdurrant@amazon.com> <20191205140123.3817-5-pdurrant@amazon.com> <20191209121726.GU980@Air-de-Roger> In-Reply-To: <20191209121726.GU980@Air-de-Roger> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.43.164.211] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Roger Pau Monn=E9 > Sent: 09 December 2019 12:17 > To: Durrant, Paul > Cc: linux-kernel@vger.kernel.org; xen-devel@lists.xenproject.org; Konrad > Rzeszutek Wilk ; Jens Axboe ; > Boris Ostrovsky ; Juergen Gross > ; Stefano Stabellini > Subject: Re: [PATCH 4/4] xen-blkback: support dynamic unbind/bind >=20 > On Thu, Dec 05, 2019 at 02:01:23PM +0000, Paul Durrant wrote: > > By simply re-attaching to shared rings during connect_ring() rather tha= n > > assuming they are freshly allocated (i.e assuming the counters are zero= ) > > it is possible for vbd instances to be unbound and re-bound from and to > > (respectively) a running guest. > > > > This has been tested by running: > > > > while true; do dd if=3D/dev/urandom of=3Dtest.img bs=3D1M count=3D1024;= done > > > > in a PV guest whilst running: > > > > while true; > > do echo vbd-$DOMID-$VBD >unbind; > > echo unbound; > > sleep 5; > > echo vbd-$DOMID-$VBD >bind; > > echo bound; > > sleep 3; > > done >=20 > So this does unbind blkback while leaving the PV interface as > connected? >=20 Yes, everything is left in place in the frontend. The backend detaches from= the ring, closes its end of the event channels, etc. but the guest can sti= ll send requests which will get serviced when the new backend attaches. Paul