Re: [PATCH 2/3] cciss: add support for blktrace

[Jens Axboe <jens.axboe@oracle.com>]

On Mon, Nov 19 2007, Mike Miller wrote:
> Patch 2 of 3
> This patch adds support for the blktrace utility. Please consider this for
> inclusion. Seems there was already a call to blk_add_trace. This patch adds
> ifdef's and includes the header file.
> 
> Signed-off-by: Mike Miller <mike.miller@hp.com>
> 
> 
> diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
> index 2ba5a89..61bc0f3 100644
> --- a/drivers/block/cciss.c
> +++ b/drivers/block/cciss.c
> @@ -41,6 +41,10 @@
>  #include <asm/uaccess.h>
>  #include <asm/io.h>
>  
> +#ifdef CONFIG_BLK_DEV_IO_TRACE
> +#include <linux/blktrace_api.h>
> +#endif /* CONFIG_BLK_DEV_IO_TRACE */
> +
>  #include <linux/dma-mapping.h>
>  #include <linux/blkdev.h>
>  #include <linux/genhd.h>
> @@ -3013,7 +3017,9 @@ after_error_processing:
>  	}
>  	cmd->rq->data_len = 0;
>  	cmd->rq->completion_data = cmd;
> +#ifdef CONFIG_BLK_DEV_IO_TRACE
>  	blk_add_trace_rq(cmd->rq->q, cmd->rq, BLK_TA_COMPLETE);
> +#endif /* CONFIG_BLK_DEV_IO_TRACE */
>  	blk_complete_request(cmd->rq);
>  }

Puzzled by this patch... What is it trying to achieve?

-- 
Jens Axboe