Re: [patch 0/2] grub-0.97: btrfs support

[Edward Shishkin <edward@redhat.com>]

Johannes Hirte wrote:
> Am Freitag 11 Dezember 2009 16:27:54 schrieb Edward Shishkin:
>   
>> Johannes Hirte wrote:
>>     
>>> Am Freitag 11 Dezember 2009 12:17:29 schrieb Edward Shishkin:
>>>       
>>>> Johannes Hirte wrote:
>>>>         
>>>>> Am Freitag 11 Dezember 2009 00:15:46 schrieb Johannes Hirte:
>>>>>           
>>>>>> Am Freitag 25 September 2009 00:06:23 schrieb Edward Shishkin:
>>>>>>             
>>>>>>> Hello everyone.
>>>>>>>               
>>>>>> ...
>>>>>>
>>>>>>             
>>>>>>> The following patches are for Fedora 10(**).
>>>>>>> The distro-independent package will be put to kernel.org a bit later.
>>>>>>>
>>>>>>>
>>>>>>> All comments, bugreports, etc. are welcome as usual.
>>>>>>>               
>>>>>> Ok, I have another comment/bugreport *g*.
>>>>>>
>>>>>> I'm testing this patch with gentoo, so the grub sources are not
>>>>>> identicaly the same. With this patches applied, grub is unable to
>>>>>> detect JFS or XFS filesystems. XFS is reported as unknown, JFS is
>>>>>> reported as btrfs. Reiserfs and ext2/3 are detected as expected.
>>>>>>             
>>>> Yes, this patch is for Fedora. For other distros
>>>> some issues are possible, so please be careful..
>>>>         
>>> I've also tested now with the fedora sources. There is the same bug. The
>>> btrfs patch breaks the filesystem detection. All filesystems after btrfs
>>> in fsys_table aren't detected. Moving btrfs to the end of fsys_table is a
>>> workaround but will interfere with FFS. So this should better be fixed in
>>> the btrfs-part of grub, so that it:
>>>
>>> a) doesn't missdetect a JFS filesystem as btrfs
>>> b) doesn't break the detection for remaining filesystems in the array.
>>>       
>> Hello.
>>
>> Yes, I confirm that xfs, etc. file systems are not detected,
>> but missdetection jfs as btrfs looks rather fantastic :)
>>
>> Please, try the attached patch. Report if any problems.
>>     
>
> The patch works, but the problem with misdetected JFS filesystem still 
> persists. It happens if the device contained a btrfs filesystem before. I 
> assume that the JFS super block starts later on the device as the btrfs one do 
> and jfs_mkfs doesn't clean the space ahead of the JFS super block. So if a JFS 
> filesystem is created on a device that contained a btrfs before, btrfs_mount 
> still detects the beginning of the old btrfs super block and reads crap later 
> on.
>   

Yup, sticky thing..

> To avoid this, btrfs detection could be placed after JFS. Are there any 
> objections against this?
>   

If so, we might want to put if after XFS,
which is also mistreated in such manner..

Thanks,
Edward.