Re: [PATCH 04/10] sd: don't use scsi_setup_blk_pc_cmnd for flush requests

[Hannes Reinecke <hare@suse.de>]

On 06/29/2014 03:34 PM, Christoph Hellwig wrote:
> Simplify handling of flush requests by setting up the command directly
> instead of initializing request fields and then calling
> scsi_setup_blk_pc_cmnd to propagate the information into the command.
>
> Also rename scsi_setup_flush_cmnd to sd_setup_flush_cmnd for consistency.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/scsi/sd.c |   20 +++++++++++++-------
>   1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index d88bdc8..620d32f 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -844,14 +844,20 @@ static int sd_setup_write_same_cmnd(struct scsi_device *sdp, struct request *rq)
>   	return ret;
>   }
>
> -static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq)
> +static int sd_setup_flush_cmnd(struct scsi_cmnd *cmd)
>   {
> -	rq->timeout *= SD_FLUSH_TIMEOUT_MULTIPLIER;
> -	rq->retries = SD_MAX_RETRIES;
> -	rq->cmd[0] = SYNCHRONIZE_CACHE;
> -	rq->cmd_len = 10;
> +	struct request *rq = cmd->request;
> +
> +	/* flush requests don't perform I/O, zero the S/G table */
> +	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
>
> -	return scsi_setup_blk_pc_cmnd(sdp, rq);
> +	cmd->cmnd[0] = SYNCHRONIZE_CACHE;
> +	cmd->cmd_len = 10;
> +	cmd->transfersize = 0;
> +	cmd->allowed = SD_MAX_RETRIES;
> +
> +	rq->timeout *= SD_FLUSH_TIMEOUT_MULTIPLIER;
> +	return BLKPREP_OK;
>   }
>
>   static void sd_uninit_command(struct scsi_cmnd *SCpnt)
> @@ -891,7 +897,7 @@ static int sd_init_command(struct scsi_cmnd *SCpnt)
>   		ret = sd_setup_write_same_cmnd(sdp, rq);
>   		goto out;
>   	} else if (rq->cmd_flags & REQ_FLUSH) {
> -		ret = scsi_setup_flush_cmnd(sdp, rq);
> +		ret = sd_setup_flush_cmnd(SCpnt);
>   		goto out;
>   	}
>   	ret = scsi_init_io(SCpnt, GFP_ATOMIC);
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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