regarding the inode64 mount option

[Felix Blyakher]

[my unsent mail from yesterday, mostly for the second blob]

On May 28, 2009, at 9:56 AM, Christoph Hellwig wrote:

> On Thu, May 28, 2009 at 02:21:44PM +0200, Michael Weissenbacher wrote:
>> Hi XFS-List!
>> I understand that the inode64 mount option allows inodes to be  
>> created beyond 1TB. There are also certain performance problems  
>> that can be cured by using this option when handling LOTS of  
>> inodes. During my tests i noticed that enabling it is like a one- 
>> way street. Inodes created with inode64 enabled aren't accessible  
>> when the option is left out.
>
> Actually they should still be accessible, we just won't create new
> inodes not addressable by 32bit inode numbers.

The inodes are indeed accessible by most apps, but those 32bit
apps using stat() (vs. stat64() ) will get confused and
may bailout processing such inodes all together.

>> Now i got a few questions:
>> - Does the inode64 option work only on 64bit architectures or is it  
>> also possible to use it with i686
>
> It is available for 32bit kernels starting with kernel 2.6.29.
>
>> - Is there a way to convert the inodes back
>
> There's an xfs_reno tool ported from IRIX to renumber the inodes.   
> I'll
> see if I can finally get it packaged.
>
>> - Why doesn't the filesystem remember that inode64 was used in the  
>> past and enable it automatically
>
> Good question.  We could introduce a flag in the superblock for this.

Agree, it's a good idea to record that inode64 was used on
previous mount, but I don't think we should enable it
automatically. Though, providing the warning will be good.

Felix