From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Novotny Subject: Re: [PATCH] qemu-xen-3.4-testing: Fix read-only image file handling Date: Thu, 03 Jun 2010 16:12:35 +0200 Message-ID: <4C07B853.3000307@redhat.com> References: <4C07B678.3020304@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C07B678.3020304@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Oh, just one more thing that should be mentioned: When you want to mount an image that is set as read-only in the domain configuration file but you omit to set mode to read-only it results into I/O errors when processing the requests. Remounting as read-only or unmounting and remounting using the `mount /dev/* /path/to/mount -o ro` shall do the mounting the correct way, i.e. with no I/O errors, so make sure you mount those disks as read-only otherwise you can be getting errors like: end_request: I/O error, dev hdb, sector 52 Buffer I/O error on device hdb1, logical block 1 lost page write due to I/O error on hdb1 and for IDE devices you'll be getting several additional DeviceFault errors since mounting the device read-write (default setting) writes some data onto a disk at the mount-time. Michal On 06/03/2010 04:04 PM, Michal Novotny wrote: > [Well, I did send an e-mail to the list using git but it's not here so > I'm forwarding the e-mail to the list for sure:] > > Hi, > this is the patch for qemu-xen-3.4-testing to fix the read-only > image file handling since the image file was always treated as > read-write which means that all the HVM guests were able to > write to all the disk images available in domain configuration > file no matter what the mode of the image was defined. This > patch fixes this functionality to honor the O_RDONLY in the > BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI > interfaces that uses it. > > It's been tested on RHEL-5 with xen-3.4-testing version of > upstream xen with xen-3.4-testing qemu implementation. > > For SCSI devices the DATA PROTECT request sense has been added > as found at: http://en.wikipedia.org/wiki/SCSI_Request_Sense_Command > > file no matter what the mode of the image was defined. This > patch fixes this functionality to honor the O_RDONLY in the > BDRV_O_ACCESS flag in block.c and also fixes the IDE and SCSI > interfaces that uses it. > > It's been tested on RHEL-5 with xen-3.4-testing version of > Michal > > Signed-off-by: Michal Novotny > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > -- Michal Novotny, RHCE Virtualization Team (xen userspace), Red Hat