Re: [PATCH] qemu-xen-3.4-testing: Fix read-only image file handling

[Michal Novotny <minovotn@redhat.com>]

Oh, one more thing I've discovered now. Since the codebase for 
qemu-xen-unstable is looking the same like for qemu-xen-3.4-testing and 
the patch is applicable without any modifications it could be working 
for xen-4.1 unstable as well, unfortunately I was not able to boot PVOPS 
kernel since it always ends up in kernel panic, maybe the missing 
drivers or something like that. Could anybody please test my patch with 
qemu-xen-unstable to see if it's working?

Thanks a lot!

Michal

On 06/03/2010 04:12 PM, Michal Novotny wrote:
> 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 <minovotn@redhat.com>
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>
>


-- 
Michal Novotny<minovotn@redhat.com>, RHCE
Virtualization Team (xen userspace), Red Hat