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

[Michal Novotny <minovotn@redhat.com>]

On 06/07/2010 03:10 PM, Michal Novotny wrote:
> On 06/07/2010 01:45 PM, Pasi Kärkkäinen wrote:
>> On Mon, Jun 07, 2010 at 01:21:21PM +0200, Michal Novotny wrote:
>>> Well, I'm still having some tools issues, mainly:
>>>
>>> Error: (111, 'Connection refused')
>>>
>>> Any guess what may be going wrong? Booted grub entry:
>>>
>>> title Red Hat Enterprise Linux Server (2.6.31.13-xen HV, nolog)
>>>          root (hd1,6)
>>>          kernel /xen-4.1-unstable.gz
>>>          module /vmlinuz-2.6.31.13 ro root=LABEL=/rhel2 rhgb quiet 
>>> selinux=0
>>>          module /initrd-2.6.31.13.img
>>>
>>> Mount is having `xenfs on /proc/xen type xenfs (rw)`. Any guess what 
>>> may
>>> be going wrong?
>>>
>>
>> Do you have xen-evtchn driver loaded?
>>
>>
>> -- Pasi
>>
>
> Well, no, and doesn't seem to be installed/probed:
>
> # modprobe xen-evtchn
> # lsmod | grep xen-evtchn
> #
>
> So there's the problem :(
>
> Michal

Oh, I'm taking this back since I found out the module is not xen-evtchn 
but xen_evtchn. So yeah, I'm having it loaded in the memory now. 
However, when I do `service xend restart` the same error is here:

[2010-06-07 17:14:09 5635] INFO (SrvDaemon:227) Xend stopped due to 
signal 15.
[2010-06-07 17:14:09 6295] INFO (SrvDaemon:332) Xend Daemon started
[2010-06-07 17:14:09 6295] INFO (SrvDaemon:336) Xend changeset: Thu May 
20 17:22:15 2010 +0100 21442:a7fcf2e35d32.
[2010-06-07 17:14:09 6295] DEBUG (tcp:96) Listening on :8002
[2010-06-07 17:14:09 6295] INFO (XendNetwork:114) Not recreating missing 
unmanaged network eth0
[2010-06-07 17:14:09 6295] INFO (XendNetwork:114) Not recreating missing 
unmanaged network eth2
[2010-06-07 17:14:09 6295] INFO (XendNetwork:114) Not recreating missing 
unmanaged network br0
[2010-06-07 17:14:09 6295] INFO (XendNetwork:114) Not recreating missing 
unmanaged network xenbr0
[2010-06-07 17:14:10 6295] DEBUG (XendCPUPool:747) recreate_active_pools
[2010-06-07 17:14:10 6295] ERROR (SrvDaemon:349) Exception starting xend 
((111, 'Connection refused'))
Traceback (most recent call last):
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvDaemon.py", line 
341, in run
     servers = SrvServer.create()
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/server/SrvServer.py", line 
258, in create
     root.putChild('xend', SrvRoot())
   File "/usr/lib64/python2.4/site-packages/xen/xend/server/SrvRoot.py", 
line 40, in __init__
     self.get(name)
   File "/usr/lib64/python2.4/site-packages/xen/web/SrvDir.py", line 84, 
in get
     val = val.getobj()
   File "/usr/lib64/python2.4/site-packages/xen/web/SrvDir.py", line 52, 
in getobj
     self.obj = klassobj()
   File "/usr/lib64/python2.4/site-packages/xen/xend/server/SrvNode.py", 
line 30, in __init__
     self.xn = XendNode.instance()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line 
1176, in instance
     inst = XendNode()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line 
163, in __init__
     self._init_cpu_pools()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendNode.py", line 
377, in _init_cpu_pools
     XendCPUPool.recreate_active_pools()
   File "/usr/lib64/python2.4/site-packages/xen/xend/XendCPUPool.py", 
line 754, in recreate_active_pools
     uuid = xstransact.Read(path, 'uuid')
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/xenstore/xstransact.py", 
line 307, in Read
     return complete(path, lambda t: t.read(*args))
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/xenstore/xstransact.py", 
line 361, in complete
     t = xstransact(path)
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/xenstore/xstransact.py", 
line 29, in __init__
     self.transaction = xshandle().transaction_start()
   File 
"/usr/lib64/python2.4/site-packages/xen/xend/xenstore/xsutil.py", line 
18, in xshandle
     xs_handle = xen.lowlevel.xs.xs()
Error: (111, 'Connection refused')

Any ideas?

Michal

>
>>> Thanks,
>>> Michal
>>>
>>> On 06/04/2010 12:42 PM, Pasi Kärkkäinen wrote:
>>>> On Fri, Jun 04, 2010 at 11:37:51AM +0200, Michal Novotny wrote:
>>>>
>>>>> 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.
>>>>>
>>>>>
>>>> What kernel version? Did you use xen/stable-2.6.32.x branch from 
>>>> xen.git?
>>>>
>>>> See my example .config files from:
>>>> http://wiki.xensource.com/xenwiki/XenParavirtOps in the 
>>>> "troubleshooting" section.
>>>>
>>>> Works on F12/F13 dom0's.
>>>>
>>>> For el5 dom0 you might need these:
>>>> http://wiki.xensource.com/xenwiki/2.6.18-to-2.6.31-and-higher
>>>>
>>>> aka
>>>> CONFIG_SYSFS_DEPRECATED=y
>>>> CONFIG_SYSFS_DEPRECATED_V2=y
>>>>
>>>> Also atm I think you need CONFIG_XEN_XENBUS_FRONTEND=y in the .config
>>>> because of the recently added pv-on-hvm drivers (you'll get build 
>>>> failure without that option),
>>>> so you need XEN_PCIDEV_FRONTEND XEN_BLKDEV_FRONTEND or 
>>>> XEN_NETDEV_FRONTEND or XEN_FBDEV_FRONTEND needs to be =y.
>>>>
>>>> -- Pasi
>>>>
>>>>
>>>>
>>>>> 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
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> 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
>>>
>> _______________________________________________
>> 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