From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48204) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VC4Op-0006H5-65 for qemu-devel@nongnu.org; Wed, 21 Aug 2013 05:08:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VC4Ok-0000Xh-2o for qemu-devel@nongnu.org; Wed, 21 Aug 2013 05:08:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52953) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VC4Oj-0000XW-RX for qemu-devel@nongnu.org; Wed, 21 Aug 2013 05:08:14 -0400 Date: Wed, 21 Aug 2013 10:08:08 +0100 From: "Daniel P. Berrange" Message-ID: <20130821090808.GB10012@redhat.com> References: <52062D34.1050804@linux.vnet.ibm.com> <520E2798.7030607@linux.vnet.ibm.com> <20130820144348.GC5536@stefanha-thinkpad.redhat.com> <20130820145740.GA5579@redhat.com> <20130821090349.GD10379@stefanha-thinkpad.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20130821090349.GD10379@stefanha-thinkpad.redhat.com> Subject: Re: [Qemu-devel] Fwd: [libvirt] virDomainAttachDevice error during disk hotplug Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Deepak C Shetty , qemu-devel@nongnu.org On Wed, Aug 21, 2013 at 11:03:49AM +0200, Stefan Hajnoczi wrote: > On Tue, Aug 20, 2013 at 03:57:40PM +0100, Daniel P. Berrange wrote: > > On Tue, Aug 20, 2013 at 04:43:48PM +0200, Stefan Hajnoczi wrote: > > > On Fri, Aug 16, 2013 at 06:52:32PM +0530, Deepak C Shetty wrote: > > > > 2) qemu-img info /var/run/vdsm/3333017d-1278-4bfb-8129-62bded257399 > > > > image: /var/run/vdsm/3333017d-1278-4bfb-8129-62bded257399 > > > > file format: qcow2 > > > > virtual size: 3.8G (4096000000 bytes) > > > > disk size: 196K > > > > cluster_size: 65536 > > > > backing file: > > > > /rhev/data-center/000065de-04b8-42e2-986c-2de664708be7/11112d24-4cda-4200-8f6d-a1d8362c70fd/images/22224c45-6504-4ea1-bd24-12340017dd32/3333017d-1278-4bfb-8129-62bded257399 > > > > backing file format: qcow2 > > > > > > Good, QEMU can parse and read the file. > > > > > > > 3) ls -l > > > > /rhev/data-center/000065de-04b8-42e2-986c-2de664708be7/11112d24-4cda-4200-8f6d-a1d8362c70fd/images/22224c45-6504-4ea1-bd24-12340017dd32/3333017d-1278-4bfb-8129-62bded257399 > > > > -r--r-----. 1 vdsm kvm 197120 Aug 10 11:59 > > > > /rhev/data-center/000065de-04b8-42e2-986c-2de664708be7/11112d24-4cda-4200-8f6d-a1d8362c70fd/images/22224c45-6504-4ea1-bd24-12340017dd32/3333017d-1278-4bfb-8129-62bded257399 > > > > > > Read-only? > > > > > > > 4) libvirtd.log snippets: > > > > > > > > 2013-08-10 11:19:41.766+0000: 1103: debug : virDomainAttachDevice:9820 : > > > > dom=0x7f92f4003f20, (VM: name=dpk_BR_vm, > > > > uuid=9999017d-1278-4bfb-8129-62bded257399), xml= > > > snapshot="no" type="file"> > > > > > > > > > > > > 22224c45-6504-4ea1-bd24-12340017dd32 > > > > > > > name="qemu" type="qcow2"/> > > > > > > > > > > I see no read-only option. > > > > > > Does it work if you make the file read-write instead? > > > > FYI this was solved in libvir-list. > > > > The image file was on tmpfs, which does not support cache=none. > > > > We hit this so often it would be a huge help if QEMU reported a > > clearer error message then "Invalid Argument" when trying cache=none > > on tmpfs. > > The kernel only tells us EINVAL but if this is a common issue we could > add a tmpfs check and print advice (note that it's only advice because > future kernel versions might lift this limitation of tmpfs). Rather than checking for tmpfs, you could simply re-try the open() call without O_DIRECT. If that passes, then you can safely issue an error message saying that the filesystem doesn't support O_DIRECT. This will make it robust to other future filesystems which may also not do O_DIRECT Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|