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

[Michal Novotny <minovotn@redhat.com>]

On 06/07/2010 03:19 PM, Pasi Kärkkäinen wrote:
> On Mon, Jun 07, 2010 at 03:14:40PM +0200, Michal Novotny wrote:
>    
>> 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?
>>
>>      
> Is xenstore running?
>
> Are there files in /proc/xen ?
>
>    

Yes to both questions. Everything seems to be OK. Also, there's option 
to turn on the debugging of xenstore, right? Do you think it could help? 
I'm going to try it now.

Michal
> -- Pasi
>
>    
>> 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
>>
>>      
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>    


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