From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40784) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e6y3k-0002sZ-Nl for qemu-devel@nongnu.org; Tue, 24 Oct 2017 08:11:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e6y3g-0003CE-OQ for qemu-devel@nongnu.org; Tue, 24 Oct 2017 08:11:52 -0400 Received: from smtp.citrix.com ([66.165.176.89]:64388) by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71) (envelope-from ) id 1e6y3g-0003BY-HI for qemu-devel@nongnu.org; Tue, 24 Oct 2017 08:11:48 -0400 Date: Tue, 24 Oct 2017 13:11:40 +0100 From: Anthony PERARD Message-ID: <20171024121140.GE1885@perard.uk.xensource.com> References: <20171002163058.15651-1-anthony.perard@citrix.com> <20171002191822.GA2707@work-vm> <20171004130349.GB9801@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171004130349.GB9801@localhost.localdomain> Subject: Re: [Qemu-devel] [PATCH] migration, xen: Fix block image lock issue on live migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, xen-devel@lists.xenproject.org, Ian Jackson , Wei Liu , Juan Quintela On Wed, Oct 04, 2017 at 03:03:49PM +0200, Kevin Wolf wrote: > Am 02.10.2017 um 21:18 hat Dr. David Alan Gilbert geschrieben: > > Adding in kwolf; it looks sane to me; Kevin? > > If I'm reading this right, this is just after the device state save. > > Is this actual migration? Because the code looks more like it's copied > and adapted from the snapshot code rather than from the actual migration > code. Well the Xen tool stack takes care of the migration, we only need to save the device states from QEMU, I guess similair to a snapshot. > If Xen doesn't use the standard mechanisms, I don't know what they need > to do. Snapshots don't need to inactivate images, but migration does. > Compared to the normal migration path, this looks very simplistic, so I > wouldn't be surprised if there was more wrong than just file locking. I realize now that if one would want to take a snapshot of a running Xen guest, this xen-save-devices-state qmp command will be called as well. So I can see a few options to better handle snapshots, we could: - Add a new parameter to xen-save-devices-state, "live_migration" which could default to 'true' so older version of Xen will still works. - Create a new qmp command that sole purpose is to call bdrv_inactivate_all, I don't know what else this command would have to do. - or just take this patch. Thanks. > This looks like it could work as a hack to the problem at hand. Whether > it is a proper solution, I can't say without investing a lot more time. -- Anthony PERARD From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony PERARD Subject: Re: [PATCH] migration, xen: Fix block image lock issue on live migration Date: Tue, 24 Oct 2017 13:11:40 +0100 Message-ID: <20171024121140.GE1885@perard.uk.xensource.com> References: <20171002163058.15651-1-anthony.perard@citrix.com> <20171002191822.GA2707@work-vm> <20171004130349.GB9801@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e6y3i-0002n9-HI for xen-devel@lists.xenproject.org; Tue, 24 Oct 2017 12:11:50 +0000 Content-Disposition: inline In-Reply-To: <20171004130349.GB9801@localhost.localdomain> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Kevin Wolf Cc: Wei Liu , Juan Quintela , Ian Jackson , "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org T24gV2VkLCBPY3QgMDQsIDIwMTcgYXQgMDM6MDM6NDlQTSArMDIwMCwgS2V2aW4gV29sZiB3cm90 ZToKPiBBbSAwMi4xMC4yMDE3IHVtIDIxOjE4IGhhdCBEci4gRGF2aWQgQWxhbiBHaWxiZXJ0IGdl c2NocmllYmVuOgo+ID4gQWRkaW5nIGluIGt3b2xmOyAgaXQgbG9va3Mgc2FuZSB0byBtZTsgS2V2 aW4/Cj4gPiBJZiBJJ20gcmVhZGluZyB0aGlzIHJpZ2h0LCB0aGlzIGlzIGp1c3QgYWZ0ZXIgdGhl IGRldmljZSBzdGF0ZSBzYXZlLgo+IAo+IElzIHRoaXMgYWN0dWFsIG1pZ3JhdGlvbj8gQmVjYXVz ZSB0aGUgY29kZSBsb29rcyBtb3JlIGxpa2UgaXQncyBjb3BpZWQKPiBhbmQgYWRhcHRlZCBmcm9t IHRoZSBzbmFwc2hvdCBjb2RlIHJhdGhlciB0aGFuIGZyb20gdGhlIGFjdHVhbCBtaWdyYXRpb24K PiBjb2RlLgoKV2VsbCB0aGUgWGVuIHRvb2wgc3RhY2sgdGFrZXMgY2FyZSBvZiB0aGUgbWlncmF0 aW9uLCB3ZSBvbmx5IG5lZWQgdG8Kc2F2ZSB0aGUgZGV2aWNlIHN0YXRlcyBmcm9tIFFFTVUsIEkg Z3Vlc3Mgc2ltaWxhaXIgdG8gYSBzbmFwc2hvdC4KCj4gSWYgWGVuIGRvZXNuJ3QgdXNlIHRoZSBz dGFuZGFyZCBtZWNoYW5pc21zLCBJIGRvbid0IGtub3cgd2hhdCB0aGV5IG5lZWQKPiB0byBkby4g U25hcHNob3RzIGRvbid0IG5lZWQgdG8gaW5hY3RpdmF0ZSBpbWFnZXMsIGJ1dCBtaWdyYXRpb24g ZG9lcy4KPiBDb21wYXJlZCB0byB0aGUgbm9ybWFsIG1pZ3JhdGlvbiBwYXRoLCB0aGlzIGxvb2tz IHZlcnkgc2ltcGxpc3RpYywgc28gSQo+IHdvdWxkbid0IGJlIHN1cnByaXNlZCBpZiB0aGVyZSB3 YXMgbW9yZSB3cm9uZyB0aGFuIGp1c3QgZmlsZSBsb2NraW5nLgoKSSByZWFsaXplIG5vdyB0aGF0 IGlmIG9uZSB3b3VsZCB3YW50IHRvIHRha2UgYSBzbmFwc2hvdCBvZiBhIHJ1bm5pbmcKWGVuIGd1 ZXN0LCB0aGlzIHhlbi1zYXZlLWRldmljZXMtc3RhdGUgcW1wIGNvbW1hbmQgd2lsbCBiZSBjYWxs ZWQgYXMKd2VsbC4KClNvIEkgY2FuIHNlZSBhIGZldyBvcHRpb25zIHRvIGJldHRlciBoYW5kbGUg c25hcHNob3RzLCB3ZSBjb3VsZDoKLSBBZGQgYSBuZXcgcGFyYW1ldGVyIHRvIHhlbi1zYXZlLWRl dmljZXMtc3RhdGUsICJsaXZlX21pZ3JhdGlvbiIgd2hpY2gKICBjb3VsZCBkZWZhdWx0IHRvICd0 cnVlJyBzbyBvbGRlciB2ZXJzaW9uIG9mIFhlbiB3aWxsIHN0aWxsIHdvcmtzLgotIENyZWF0ZSBh IG5ldyBxbXAgY29tbWFuZCB0aGF0IHNvbGUgcHVycG9zZSBpcyB0byBjYWxsCiAgYmRydl9pbmFj dGl2YXRlX2FsbCwgSSBkb24ndCBrbm93IHdoYXQgZWxzZSB0aGlzIGNvbW1hbmQgd291bGQgaGF2 ZSB0bwogIGRvLgotIG9yIGp1c3QgdGFrZSB0aGlzIHBhdGNoLgoKVGhhbmtzLgoKPiBUaGlzIGxv b2tzIGxpa2UgaXQgY291bGQgd29yayBhcyBhIGhhY2sgdG8gdGhlIHByb2JsZW0gYXQgaGFuZC4g V2hldGhlcgo+IGl0IGlzIGEgcHJvcGVyIHNvbHV0aW9uLCBJIGNhbid0IHNheSB3aXRob3V0IGlu dmVzdGluZyBhIGxvdCBtb3JlIHRpbWUuCgoKLS0gCkFudGhvbnkgUEVSQVJECgpfX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpYZW4tZGV2ZWwgbWFpbGluZyBs aXN0Clhlbi1kZXZlbEBsaXN0cy54ZW4ub3JnCmh0dHBzOi8vbGlzdHMueGVuLm9yZy94ZW4tZGV2 ZWwK