Re: [PATCH 3/4] xfs: allow assigning the tail lsn with the AIL lock held

[Dave Chinner <david@xxxxxxxxxxxxx>]

On Fri, Mar 16, 2012 at 01:55:44PM -0400, Christoph Hellwig wrote:
> Provide a variant of xlog_assign_tail_lsn that has the AIL lock already
> held.  By doing so we do an additional atomic_read + atomic_set under
> the lock, which comes down to two instructions.
> 
> Switch xfs_trans_ail_update_bulk and xfs_trans_ail_delete_bulk to the
> new version to reduce the number of lock roundtrips, and prepare for
> a new addition that would require a third lock roundtrip in
> xfs_trans_ail_delete_bulk.

What new addition is that? I don't see it in this patchset (maybe
I'm just blind), so maybe this isn't necessary in the commit
message?


Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx