Re: [PATCH 12/23] scsi_dh_alua: switch to scsi_execute_req_flags()

[Ewan Milne <emilne@redhat.com>]

On Thu, 2015-08-27 at 14:41 +0200, Hannes Reinecke wrote:
> All commands are issued synchronously, so no need to open-code
> scsi_execute_req_flags() anymore. And we can get rid of the
> static sense code structure element.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  drivers/scsi/device_handler/scsi_dh_alua.c | 124 ++++++++---------------------
>  1 file changed, 34 insertions(+), 90 deletions(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index fd0385e..ef4363a 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -75,8 +75,6 @@ struct alua_dh_data {
>  	unsigned char		*buff;
>  	int			bufflen;
>  	unsigned char		transition_tmo;
> -	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];
> -	int			senselen;
>  	struct scsi_device	*sdev;
>  	activate_complete	callback_fn;
>  	void			*callback_data;
> @@ -103,72 +101,30 @@ static int realloc_buffer(struct alua_dh_data *h, unsigned len)
>  	return 0;
>  }
>  
> -static struct request *get_alua_req(struct scsi_device *sdev,
> -				    void *buffer, unsigned buflen, int rw)
> -{
> -	struct request *rq;
> -	struct request_queue *q = sdev->request_queue;
> -
> -	rq = blk_get_request(q, rw, GFP_NOIO);
> -
> -	if (IS_ERR(rq)) {
> -		sdev_printk(KERN_INFO, sdev,
> -			    "%s: blk_get_request failed\n", __func__);
> -		return NULL;
> -	}
> -	blk_rq_set_block_pc(rq);
> -
> -	if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
> -		blk_put_request(rq);
> -		sdev_printk(KERN_INFO, sdev,
> -			    "%s: blk_rq_map_kern failed\n", __func__);
> -		return NULL;
> -	}
> -
> -	rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
> -			 REQ_FAILFAST_DRIVER;
> -	rq->retries = ALUA_FAILOVER_RETRIES;
> -	rq->timeout = ALUA_FAILOVER_TIMEOUT * HZ;
> -
> -	return rq;
> -}
> -
>  /*
>   * 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, unsigned char *buff,
> -			    int bufflen, unsigned char *sense, int flags)
> +static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
> +		       int bufflen, struct scsi_sense_hdr *sshdr, int flags)
>  {
> -	struct request *rq;
> -	int err = 0;
> -
> -	rq = get_alua_req(sdev, buff, bufflen, READ);
> -	if (!rq) {
> -		err = DRIVER_BUSY << 24;
> -		goto done;
> -	}
> +	u8 cdb[16];

See below.

> +	int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
> +		REQ_FAILFAST_DRIVER;
>  
>  	/* Prepare the command. */
> -	rq->cmd[0] = MAINTENANCE_IN;
> +	memset(cdb, 0x0, 16);

See below.

> +	cdb[0] = MAINTENANCE_IN;
>  	if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
> -		rq->cmd[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
> +		cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
>  	else
> -		rq->cmd[1] = MI_REPORT_TARGET_PGS;
> -	put_unaligned_be32(bufflen, &rq->cmd[6]);
> -	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_IN);
> -
> -	rq->sense = sense;
> -	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
> -	rq->sense_len = 0;
> +		cdb[1] = MI_REPORT_TARGET_PGS;
> +	put_unaligned_be32(bufflen, &cdb[6]);
>  
> -	blk_execute_rq(rq->q, NULL, rq, 1);
> -	if (rq->errors)
> -		err = rq->errors;
> -
> -	blk_put_request(rq);
> -done:
> -	return err;
> +	return scsi_execute_req_flags(sdev, cdb, DMA_FROM_DEVICE,
> +				      buff, bufflen, sshdr,
> +				      ALUA_FAILOVER_TIMEOUT * HZ,
> +				      ALUA_FAILOVER_RETRIES, NULL, req_flags);
>  }
>  
>  /*
> @@ -178,40 +134,30 @@ done:
>   * to 'active/optimized' and let the array firmware figure out
>   * the states of the remaining groups.
>   */
> -static unsigned submit_stpg(struct scsi_device *sdev, int group_id,
> -			    unsigned char *sense)
> +static int submit_stpg(struct scsi_device *sdev, int group_id,
> +		       struct scsi_sense_hdr *sshdr)
>  {
> -	struct request *rq;
> +	u8 cdb[COMMAND_SIZE(MAINTENANCE_OUT)];
>  	unsigned char stpg_data[8];
>  	int stpg_len = 8;
> -	int err = 0;
> +	int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
> +		REQ_FAILFAST_DRIVER;
>  
>  	/* Prepare the data buffer */
>  	memset(stpg_data, 0, stpg_len);
>  	stpg_data[4] = TPGS_STATE_OPTIMIZED & 0x0f;
>  	put_unaligned_be16(group_id, &stpg_data[6]);
>  
> -	rq = get_alua_req(sdev, stpg_data, stpg_len, WRITE);
> -	if (!rq)
> -		return DRIVER_BUSY << 24;
> -
>  	/* Prepare the command. */
> -	rq->cmd[0] = MAINTENANCE_OUT;
> -	rq->cmd[1] = MO_SET_TARGET_PGS;
> -	put_unaligned_be32(stpg_len, &rq->cmd[6]);
> -	rq->cmd_len = COMMAND_SIZE(MAINTENANCE_OUT);
> -
> -	rq->sense = sense;
> -	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
> -	rq->sense_len = 0;
> -
> -	blk_execute_rq(rq->q, NULL, rq, 1);
> -	if (rq->errors)
> -		err = rq->errors;
> -
> -	blk_put_request(rq);
> -
> -	return err;
> +	memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_OUT));

See below.

> +	cdb[0] = MAINTENANCE_OUT;
> +	cdb[1] = MO_SET_TARGET_PGS;
> +	put_unaligned_be32(stpg_len, &cdb[6]);
> +
> +	return scsi_execute_req_flags(sdev, cdb, DMA_TO_DEVICE,
> +				      stpg_data, stpg_len,
> +				      sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
> +				      ALUA_FAILOVER_RETRIES, NULL, req_flags);
>  }
>  
>  /*
> @@ -447,15 +393,14 @@ 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->buff, h->bufflen, h->sense, h->flags);
> +	retval = submit_rtpg(sdev, h->buff, h->bufflen, &sense_hdr, h->flags);
>  
>  	if (retval) {
> -		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
> -					  &sense_hdr)) {
> +		if (!scsi_sense_valid(&sense_hdr)) {
>  			sdev_printk(KERN_INFO, sdev,
>  				    "%s: rtpg failed, result %d\n",
>  				    ALUA_DH_NAME, retval);
> -			if (driver_byte(retval) == DRIVER_BUSY)
> +			if (driver_byte(retval) == DRIVER_ERROR)
>  				err = SCSI_DH_DEV_TEMP_BUSY;
>  			else
>  				err = SCSI_DH_IO;
> @@ -616,15 +561,14 @@ static unsigned alua_stpg(struct scsi_device *sdev, struct alua_dh_data *h)
>  	}
>  	/* Set state to transitioning */
>  	h->state = TPGS_STATE_TRANSITIONING;
> -	retval = submit_stpg(sdev, h->group_id, h->sense);
> +	retval = submit_stpg(sdev, h->group_id, &sense_hdr);
>  
>  	if (retval) {
> -		if (!scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE,
> -					  &sense_hdr)) {
> +		if (!scsi_sense_valid(&sense_hdr)) {
>  			sdev_printk(KERN_INFO, sdev,
>  				    "%s: stpg failed, result %d",
>  				    ALUA_DH_NAME, retval);
> -			if (driver_byte(retval) == DRIVER_BUSY)
> +			if (driver_byte(retval) == DRIVER_ERROR)
>  				return SCSI_DH_DEV_TEMP_BUSY;
>  		} else {
>  			sdev_printk(KERN_INFO, h->sdev, "%s: stpg failed\n",

u8 cdb[16] and u8 cdb[COMMAND_SIZE(MAINTENANCE_OUT)] in submit_rtpg/submit_stpg
should be consistent.  I would stick with COMMAND_SIZE.  16 is wrong, RTPG is
a 12-byte MAINTENANCE_IN service action.

memset() of cdb in submit_rtpg/submit_stpg should use sizeof(cdb) rather than
a hardcoded value.

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