[PATCH, RFC] xfs: batched discard support

[Christoph Hellwig]

On Sun, Aug 16, 2009 at 09:59:32AM -0400, Mark Lord wrote:
> Okay, I got Matthews patches updated onto 2.6.31, and fixed the incompatibilities
> between those and the XFS TRIM patch (from Christoph), plus a sector_t printk issue.
>
> My apologies for attachments, but I am attaching the updated Christoph patch,
> as well as my hacked-up forward-port of Matthew's patches.
>
> Not pretty, but they work.  :)
>
> Now.. running Christoph's "xfs trim" on a 4.6GB mostly already-trimmed
> XFS partition gave this for the first time around:

> The problem is, it still issues TRIMs to the LLD one extent at a time.
> Compare this with doing it all in a single TRIM command
> with the wiper.sh script (filesystem unmounted):

I could do a variant which issues a single TRIM, but that would require
us to lock out all other allocations for the time the trim takes.  I'll
hack that up once I get some time.