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Re: How to run xfstests against multipath disks on SuSE?

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: How to run xfstests against multipath disks on SuSE?
From: Eric Sandeen <sandeen@xxxxxxxxxx>
Date: Tue, 27 Nov 2012 14:37:09 -0600
Cc: Ryan Wang <openspace.wang@xxxxxxxxx>, "Theodore Ts'o" <tytso@xxxxxxx>, Lukáš Czerner <lczerner@xxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <20121127203537.GM6434@dastard>
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On 11/27/12 2:35 PM, Dave Chinner wrote:
> On Tue, Nov 27, 2012 at 11:08:30AM -0600, Eric Sandeen wrote:
>> On 11/26/12 9:14 PM, Dave Chinner wrote:
>>> On Tue, Nov 27, 2012 at 09:20:47AM +0800, Ryan Wang wrote:
>>>> 2012/11/26 Theodore Ts'o <tytso@xxxxxxx>:
>>>>> On Mon, Nov 26, 2012 at 02:43:40PM +0100, Lukáš Czerner wrote:
>>>>>>> The I checked the script common.rc, and found that it uses
>>>>>>> df to determine the filesystem type and it uses the realpath
>>>>>>> "/dev/dm-0" instead of "/dev/mapper/mpatha", while df always
>>>>>>> shows "devtmpfs" instead of "ext4" for /dev/dm-0.
>>>>>>> I run "mount" and found that devtmpfs is mount on /dev/ on opensuse
>>>>>>> ***by default***. Even though  I run "mount -t btrfs /dev/dm-0 
>>>>>>> /somedir",
>>>>>>> df still showed devtmpfs.
>>>>>>> Any ideas to kick off the xfstests?
>>>>> At least with the df which ships with Debian Testing, df will display
>>>>> the file system in use if it matches the device name which is
>>>>> /etc/mtab.  It looks the issue is that mount is canonicalizing the
>>>>> device name to be the human friendly version:
>>>>> # ls -l /dev/mapper/closure-bigscratch
>>>>> 0 lrwxrwxrwx 1 root root 7 Nov 16 15:15 /dev/mapper/closure-bigscratch -> 
>>>>> ../dm-7
>>>>> <tytso.root@closure> {/home/tytso/bin}, level 2
>>>>> # mount /dev/dm-7 /u2
>>>>> # df /u2
>>>>> Filesystem                     1K-blocks   Used Available Use% Mounted on
>>>>> /dev/mapper/closure-bigscratch  52403200 224772  52178428   1% /u2
>>>>> # grep /u2 /etc/mtab
>>>>> /dev/mapper/closure-bigscratch /u2 xfs rw,relatime,attr2,inode64,noquota 
>>>>> 0 0
>>>>> So the simplest solution is to just use /dev/mapper/mpatha instead of
>>>>> insisting on using /dev/dm-0.  That's what I do....
>>>> In xfstests/common.rc, it will use realpath to obtain /dev/dm-0, even if 
>>>> you
>>>> specified /dev/mapper/mpatha.
>>>> My problem is in SuSE, the devtmpfs is mounted on /dev by default, seems
>>>> used by udev. And df reports devtmpfs on /dev/dm-0, instead of ext4.
>>> What version of xfstests are you using? Do you have a
>>> "README.device-mapper" file in the base directory? If not, upgrade
>>> to the latest version and retry.
>>> $ gl -n 1 -p 0a81886
>>> commit 0a818862bb74932e15971ec8bedb55765ec3a3f6
>>> Author: Christoph Hellwig <hch@xxxxxx>
>>> Date:   Wed May 4 16:28:32 2011 +0200
>>>     xfstests: support post-udev device mapper nodes
>>>     Because of udevs complaining device mapper now creates /dev/dm-N as the 
>>> real
>>>     device nodes, and just symlinks the /dev/mapper/ names to it.  This 
>>> would be
>>>     easy if everything used the /dev/mapper clear names, but most system 
>>> utilities
>>>     translate them back to the /dev/mapper/ names and thus confuse various 
>>> test
>>>     cases.  Add support to _is_block_dev to read symlinks, and add 
>>> documentation
>>>     on how to run xfstests on device mapper volumes.
>>>     Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>>>     Reviewed-by: Alex Elder <aelder@xxxxxxx>
>>> Cheers,
>>> Dave.
>> Recent "realpath" changes also went in:
>> b03c662399956609934ff063e9064e15dc7459ac xfstests: fix to build src/realpath 
>> and the correct the existence of target devices
>> d5ea873fcbf00b841f0511a26fb341364a5c6425 xfstests: resolve symlinked devices 
>> to real paths
>> so either of those could have broken and/or fixed it for you :)
> Yup, those are almost certainly the patches that broke device mapper
> support. There' aren't changes to common.rc, so I didn't notice them.
> They basically override the fix that Christoph made to support
> /dev/mapper links properly.
> I'd suggest a revert is in order, the two patches above were part
> of Rich's hovering of old, unreviewed patches. This problem was
> already fixed in a different way by Christoph, so adding these
> patches was wrong.

Fine with me ...

Ryan, can you test w/o those, and if it works -

Rich, can you revert those please?


> Cheers,
> Dave.

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