[Precise][PATCH] mtip32xx: removed the irrelevant argument of mtip_hw_submit_io() and the unused member of struct driver_data

[Tim Gardner]

On 03/30/2012 10:14 AM, James M Leddy wrote:
> From: Asai Thambi S P <asamymuthupa at micron.com>
> 
> Removed the following:
> 	* irrelevant argument 'barrier' of mtip_hw_submit_io()
> 	* unused member 'eh_active' of struct driver_data
> 
> Signed-off-by: Asai Thambi S P <asamymuthupa at micron.com>
> Signed-off-by: Sam Bradshaw <sbradshaw at micron.com>
> Signed-off-by: Jens Axboe <axboe at kernel.dk>
> (cherry picked from commit 4e8670e26135d8fbfd5e084fddc1a8ed9f8eb4cb)
> 
> From the merge:
> 
>   - Killing the barrier part of mtip32xx.  It doesn't really support
>     barriers, and it doesn't need them (writes are fully ordered).
> 
> Follow on from mtip32xx support that was added in 3.2.0-13.22.
> I have compile tested.
> 
> Signed-off-by: James M Leddy <james.leddy at canonical.com>
> ---
>  drivers/block/mtip32xx/mtip32xx.c |   11 +++++------
>  drivers/block/mtip32xx/mtip32xx.h |    5 -----
>  2 files changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
> index b74eab7..8eb81c9 100644
> --- a/drivers/block/mtip32xx/mtip32xx.c
> +++ b/drivers/block/mtip32xx/mtip32xx.c
> @@ -2068,8 +2068,6 @@ static int mtip_hw_ioctl(struct driver_data *dd, unsigned int cmd,
>   *	     when the read completes.
>   * @data     Callback data passed to the callback function
>   *	     when the read completes.
> - * @barrier  If non-zero, this command must be completed before
> - *	     issuing any other commands.
>   * @dir      Direction (read or write)
>   *
>   * return value
> @@ -2077,7 +2075,7 @@ static int mtip_hw_ioctl(struct driver_data *dd, unsigned int cmd,
>   */
>  static void mtip_hw_submit_io(struct driver_data *dd, sector_t start,
>  			      int nsect, int nents, int tag, void *callback,
> -			      void *data, int barrier, int dir)
> +			      void *data, int dir)
>  {
>  	struct host_to_dev_fis	*fis;
>  	struct mtip_port *port = dd->port;
> @@ -2108,8 +2106,6 @@ static void mtip_hw_submit_io(struct driver_data *dd, sector_t start,
>  	*((unsigned int *) &fis->lba_low) = (start & 0xFFFFFF);
>  	*((unsigned int *) &fis->lba_low_ex) = ((start >> 24) & 0xFFFFFF);
>  	fis->device	 = 1 << 6;
> -	if (barrier)
> -		fis->device |= FUA_BIT;
>  	fis->features    = nsect & 0xFF;
>  	fis->features_ex = (nsect >> 8) & 0xFF;
>  	fis->sect_count  = ((tag << 3) | (tag >> 5));
> @@ -3087,7 +3083,6 @@ static void mtip_make_request(struct request_queue *queue, struct bio *bio)
>  				tag,
>  				bio_endio,
>  				bio,
> -				bio->bi_rw & REQ_FUA,
>  				bio_data_dir(bio));
>  	} else
>  		bio_io_error(bio);
> @@ -3187,6 +3182,10 @@ skip_create_disk:
>  	blk_queue_max_segments(dd->queue, MTIP_MAX_SG);
>  	blk_queue_physical_block_size(dd->queue, 4096);
>  	blk_queue_io_min(dd->queue, 4096);
> +	/*
> +	 * write back cache is not supported in the device. FUA depends on
> +	 * write back cache support, hence setting flush support to zero.
> +	 */
>  	blk_queue_flush(dd->queue, 0);
>  
>  	/* Set the capacity of the device in 512 byte sectors. */
> diff --git a/drivers/block/mtip32xx/mtip32xx.h b/drivers/block/mtip32xx/mtip32xx.h
> index 723d7c4..e0554a8 100644
> --- a/drivers/block/mtip32xx/mtip32xx.h
> +++ b/drivers/block/mtip32xx/mtip32xx.h
> @@ -104,9 +104,6 @@
>  /* BAR number used to access the HBA registers. */
>  #define MTIP_ABAR		5
>  
> -/* Forced Unit Access Bit */
> -#define FUA_BIT			0x80
> -
>  #ifdef DEBUG
>   #define dbg_printk(format, arg...)	\
>  	printk(pr_fmt(format), ##arg);
> @@ -415,8 +412,6 @@ struct driver_data {
>  
>  	atomic_t resumeflag; /* Atomic variable to track suspend/resume */
>  
> -	atomic_t eh_active; /* Flag for error handling tracking */
> -
>  	struct task_struct *mtip_svc_handler; /* task_struct of svc thd */
>  };
>  

Does this have an actual impact on driver performance or functionality ?

-- 
Tim Gardner tim.gardner at canonical.com