Re: [PATCH] iscsi tcp set queue dma alignment to zero

[Mike Christie <michaelc@cs.wisc.edu>]

Pete Wyckoff wrote:
> Add a slave_configure function to iSCSI TCP to remove any DMA
> alignment restriction.  This permits the use of direct IO from
> arbitrary addresses.
> 
> Signed-off-by: Pete Wyckoff <pw@osc.edu>
> ---
>  drivers/scsi/iscsi_tcp.c |   11 +++++++++++
>  1 files changed, 11 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
> index 4376840..f48eedd 100644
> --- a/drivers/scsi/iscsi_tcp.c
> +++ b/drivers/scsi/iscsi_tcp.c
> @@ -2132,6 +2132,16 @@ static void iscsi_tcp_session_destroy(struct iscsi_cls_session *cls_session)
>  	iscsi_session_teardown(cls_session);
>  }
>  
> +/*
> + * New device attached.  Turn off the DMA alignment restriction on
> + * the request queue.
> + */
> +static int iscsi_tcp_slave_configure(struct scsi_device *sdev)
> +{
> +	blk_queue_dma_alignment(sdev->request_queue, 0);
> +	return 0;
> +}
> +

I think the comments are not needed, but that is not a big deal. I will
put this in my tree and send it to James if he does not pick it up from
linux-scsi.

Thanks for the patch.

Erez, I do not think ib_iser should have any limit either (I only looked
at the code for a little bit though). You may want to do the the same
for iser.