[PATCH, RFC] xfs: batched discard support

[Christoph Hellwig]

On Sun, Aug 16, 2009 at 09:00:35AM -0400, Mark Lord wrote:
> Okay, this gives me ENOSYS now --> discard/trim support is missing from
> the lower layers.

ENOSYS or EOPNOTSUPP?

> 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.

Hmm.  That was kinda the reason why I didn't want to post stuff yet.  In
current mainline only MTD implements the prepare_discard_fn, and we'll
need it implemented and working.  I think Matthews patches should be
sufficient, unless they have some ATA revision check to not issue the
TRIM for your device.