[PATCH, RFC] xfs: batched discard support

[Mark Lord]

Christoph Hellwig wrote:
> On Sat, Aug 15, 2009 at 10:19:21PM -0400, Mark Lord wrote:
>> Mark Lord wrote:
>>> Christoph Hellwig wrote:
>> ..
>>>> Mark, any chance to try it?  Just create an XFS filesystem, age it a
>>>> bit and then call the attached little trim.c program on the mountmoint
>>>> (or any file inside the filesystem for that matter)
>>> ..
>>>
>>> Looking at it now.  Thanks, Christoph!
>> ..
>>
>> Fails to work on 64-bit kernel w/ 32-bit userspace (no compat ioctl).
>> Rebuilding with 32-bit kernel now..
> 
> The actual ioctl is compatible, just add the
> 
> 	case XFS_IOC_TRIM:
> 		return xfs_ioc_trim(mp, arg);
> 
> to xfs_file_compat_ioctl().  I'll add this to the next spin of the patch.
..

Okay, this gives me ENOSYS now --> discard/trim support is missing from
the lower layers.

What other patches do I need to make this work?

The latest from Matthew's discard tree (May 2009) don't appear to be sufficient,
even after updating them for 2.6.31-rc6.

???