[PATCH 5/5] xfs: use shared ilock mode for direct IO writes by default

[Mark Tinguely]

On 03/27/12 09:34, Christoph Hellwig wrote:
> From: Dave Chinner<dchinner at redhat.com>
>
> For the direct IO write path, we only really need the ilock to be taken in
> exclusive mode during IO submission if we need to do extent allocation
> instaled of all the time.
>
> Change the block mapping code to take the ilock in shared mode for the
> initial block mapping, and only retake it exclusively when we actually
> have to perform extent allocations.  We were already dropping the ilock
> for the transaction allocation, so this doesn't introduce new race windows.
>
> Based on an earlier patch from Dave Chinner.
>
> Signed-off-by: Christoph Hellwig<hch at lst.de>


Looks good.

Reviewed-by: Mark Tinguely <tinguely at sgi.com>