Re: [PATCH 08/23] scsi_dh_alua: use flag for RTPG extended header

[Ewan Milne <emilne@redhat.com>]

On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote:
> We should be using a flag when RTPG extended header is not
> supported, that saves us sending RTPG twice for older arrays.
> 
> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  drivers/scsi/device_handler/scsi_dh_alua.c | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 25c2045..9d8fc53 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -59,8 +59,9 @@
>  #define ALUA_FAILOVER_TIMEOUT		60
>  #define ALUA_FAILOVER_RETRIES		5
>  
> -/* flags passed from user level */
> +/* device handler flags */
>  #define ALUA_OPTIMIZE_STPG		1
> +#define ALUA_RTPG_EXT_HDR_UNSUPP	2
>  
>  struct alua_dh_data {
>  	int			group_id;
> @@ -135,8 +136,7 @@ static struct request *get_alua_req(struct scsi_device *sdev,
>   * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
>   * @sdev: sdev the command should be sent to
>   */
> -static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
> -			    bool rtpg_ext_hdr_req)
> +static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
>  {
>  	struct request *rq;
>  	int err = 0;
> @@ -149,7 +149,7 @@ static unsigned submit_rtpg(struct scsi_device *sdev, struct alua_dh_data *h,
>  
>  	/* Prepare the command. */
>  	rq->cmd[0] = MAINTENANCE_IN;
> -	if (rtpg_ext_hdr_req)
> +	if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP))
>  		rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
>  	else
>  		rq->cmd[1] = MI_REPORT_TARGET_PGS;
> @@ -487,7 +487,6 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
>  	int len, k, off, valid_states = 0;
>  	unsigned char *ucp;
>  	unsigned err, retval;
> -	bool rtpg_ext_hdr_req = 1;
>  	unsigned long expiry, interval = 0;
>  	unsigned int tpg_desc_tbl_off;
>  	unsigned char orig_transition_tmo;
> @@ -498,7 +497,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
>  		expiry = round_jiffies_up(jiffies + h->transition_tmo * HZ);
>  
>   retry:
> -	retval = submit_rtpg(sdev, h, rtpg_ext_hdr_req);
> +	retval = submit_rtpg(sdev, h);
>  
>  	if (retval) {
>  		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
> @@ -521,10 +520,10 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_
>  		 * The retry without rtpg_ext_hdr_req set
>  		 * handles this.
>  		 */
> -		if (rtpg_ext_hdr_req == 1 &&
> +		if (!(h->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
>  		    sense_hdr.sense_key == ILLEGAL_REQUEST &&
>  		    sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
> -			rtpg_ext_hdr_req = 0;
> +			h->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
>  			goto retry;
>  		}
>  

Reviewed-by: Ewan D. Milne <emilne@redhat.com>