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

[Michal Novotny <minovotn@redhat.com>]

On 06/07/2010 03:21 PM, Michal Novotny wrote:
> 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

Well, I don't know what was wrong but when I turned on the debugging it 
was finally working fine to run xen daemon and also when I killed 
xenstore and turned off the debugging. `xm list` was working fine but I 
don't know why so it's a kind of magic to me. Nevertheless, it appears 
to be working fine by now.

Thanks for your help!
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
>>>
>> _______________________________________________
>> 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