Re: [PATCH 04/18] scsi_dh_alua: Use vpd_pg83 information

[Johannes Thumshirn <jthumshirn@suse.com>]

On Tue, 2015-12-01 at 10:16 +0100, Hannes Reinecke wrote:
> The SCSI device now has the VPD page 0x83 information attached,
> so there is no need to query it again.
> 
> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  drivers/scsi/device_handler/scsi_dh_alua.c | 87 +++++++---------------------
> --
>  1 file changed, 18 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
> b/drivers/scsi/device_handler/scsi_dh_alua.c
> index 7d01ef0..9b3b2f7 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -131,43 +131,6 @@ static struct request *get_alua_req(struct scsi_device
> *sdev,
>  }
>  
>  /*
> - * submit_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command
> - * @sdev: sdev the command should be sent to
> - */
> -static int submit_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data
> *h)
> -{
> -	struct request *rq;
> -	int err = SCSI_DH_RES_TEMP_UNAVAIL;
> -
> -	rq = get_alua_req(sdev, h->buff, h->bufflen, READ);
> -	if (!rq)
> -		goto done;
> -
> -	/* Prepare the command. */
> -	rq->cmd[0] = INQUIRY;
> -	rq->cmd[1] = 1;
> -	rq->cmd[2] = 0x83;
> -	rq->cmd[4] = h->bufflen;
> -	rq->cmd_len = COMMAND_SIZE(INQUIRY);
> -
> -	rq->sense = h->sense;
> -	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
> -	rq->sense_len = h->senselen = 0;
> -
> -	err = blk_execute_rq(rq->q, NULL, rq, 1);
> -	if (err == -EIO) {
> -		sdev_printk(KERN_INFO, sdev,
> -			    "%s: evpd inquiry failed with %x\n",
> -			    ALUA_DH_NAME, rq->errors);
> -		h->senselen = rq->sense_len;
> -		err = SCSI_DH_IO;
> -	}
> -	blk_put_request(rq);
> -done:
> -	return err;
> -}
> -
> -/*
>   * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
>   * @sdev: sdev the command should be sent to
>   */
> @@ -359,43 +322,29 @@ static int alua_check_tpgs(struct scsi_device *sdev,
> struct alua_dh_data *h)
>  }
>  
>  /*
> - * alua_vpd_inquiry - Evaluate INQUIRY vpd page 0x83
> + * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
>   * @sdev: device to be checked
>   *
>   * Extract the relative target port and the target port group
>   * descriptor from the list of identificators.
>   */
> -static int alua_vpd_inquiry(struct scsi_device *sdev, struct alua_dh_data
> *h)
> +static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h)
>  {
> -	int len;
> -	unsigned err;
>  	unsigned char *d;
> +	unsigned char __rcu *vpd_pg83;
>  
> - retry:
> -	err = submit_vpd_inquiry(sdev, h);
> -
> -	if (err != SCSI_DH_OK)
> -		return err;
> -
> -	/* Check if vpd page exceeds initial buffer */
> -	len = (h->buff[2] << 8) + h->buff[3] + 4;
> -	if (len > h->bufflen) {
> -		/* Resubmit with the correct length */
> -		if (realloc_buffer(h, len)) {
> -			sdev_printk(KERN_WARNING, sdev,
> -				    "%s: kmalloc buffer failed\n",
> -				    ALUA_DH_NAME);
> -			/* Temporary failure, bypass */
> -			return SCSI_DH_DEV_TEMP_BUSY;
> -		}
> -		goto retry;
> +	rcu_read_lock();
> +	if (!rcu_dereference(sdev->vpd_pg83)){
> +		rcu_read_unlock();
> +		return SCSI_DH_DEV_UNSUPP;
>  	}
>  
>  	/*
> -	 * Now look for the correct descriptor.
> +	 * Look for the correct descriptor.
>  	 */
> -	d = h->buff + 4;
> -	while (d < h->buff + len) {
> +	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
> +	d = vpd_pg83 + 4;
> +	while (d < vpd_pg83 + sdev->vpd_pg83_len) {
>  		switch (d[1] & 0xf) {
>  		case 0x4:
>  			/* Relative target port */
> @@ -410,6 +359,7 @@ static int alua_vpd_inquiry(struct scsi_device *sdev,
> struct alua_dh_data *h)
>  		}
>  		d += d[3] + 4;
>  	}
> +	rcu_read_unlock();
>  
>  	if (h->group_id == -1) {
>  		/*
> @@ -422,14 +372,13 @@ static int alua_vpd_inquiry(struct scsi_device *sdev,
> struct alua_dh_data *h)
>  			    ALUA_DH_NAME);
>  		h->state = TPGS_STATE_OPTIMIZED;
>  		h->tpgs = TPGS_MODE_NONE;
> -		err = SCSI_DH_DEV_UNSUPP;
> -	} else {
> -		sdev_printk(KERN_INFO, sdev,
> -			    "%s: port group %02x rel port %02x\n",
> -			    ALUA_DH_NAME, h->group_id, h->rel_port);
> +		return SCSI_DH_DEV_UNSUPP;
>  	}
> +	sdev_printk(KERN_INFO, sdev,
> +		    "%s: port group %02x rel port %02x\n",
> +		    ALUA_DH_NAME, h->group_id, h->rel_port);
>  
> -	return err;
> +	return 0;
>  }
>  
>  static char print_alua_state(int state)
> @@ -692,7 +641,7 @@ static int alua_initialize(struct scsi_device *sdev,
> struct alua_dh_data *h)
>  	if (err != SCSI_DH_OK)
>  		goto out;
>  
> -	err = alua_vpd_inquiry(sdev, h);
> +	err = alua_check_vpd(sdev, h);
>  	if (err != SCSI_DH_OK)
>  		goto out;
>  

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
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