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Commit d7c48feb authored by Hannes Reinecke's avatar Hannes Reinecke Committed by James Bottomley
Browse files

[SCSI] scsi_dh_alua: Evaluate TPGS setting from inquiry data 



Instead of issuing a standard inquiry from within the
alua device handler we can evaluate the TPGS setting from
the existing inquiry data of the sdev and save us the I/O.

Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent ac81c6a8

drivers/scsi/device_handler/scsi_dh_alua.c

+6 −49
Original line number Diff line number Diff line
@@ -127,43 +127,6 @@ static struct request *get_alua_req(struct scsi_device *sdev, 
	return rq;

}



/*

 * submit_std_inquiry - Issue a standard INQUIRY command

 * @sdev: sdev the command should be send to

 */

static int submit_std_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->inq, ALUA_INQUIRY_SIZE, READ);

	if (!rq)

		goto done;



	/* Prepare the command. */

	rq->cmd[0] = INQUIRY;

	rq->cmd[1] = 0;

	rq->cmd[2] = 0;

	rq->cmd[4] = ALUA_INQUIRY_SIZE;

	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: std 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_vpd_inquiry - Issue an INQUIRY VPD page 0x83 command

 * @sdev: sdev the command should be sent to
@@ -338,23 +301,17 @@ static unsigned submit_stpg(struct alua_dh_data *h) 
}



/*

 * alua_std_inquiry - Evaluate standard INQUIRY command

 * alua_check_tpgs - Evaluate TPGS setting

 * @sdev: device to be checked

 *

 * Just extract the TPGS setting to find out if ALUA

 * Examine the TPGS setting of the sdev to find out if ALUA

 * is supported.

 */

static int alua_std_inquiry(struct scsi_device *sdev, struct alua_dh_data *h)

static int alua_check_tpgs(struct scsi_device *sdev, struct alua_dh_data *h)

{

	int err;



	err = submit_std_inquiry(sdev, h);



	if (err != SCSI_DH_OK)

		return err;

	int err = SCSI_DH_OK;



	/* Check TPGS setting */

	h->tpgs = (h->inq[5] >> 4) & 0x3;

	h->tpgs = scsi_device_tpgs(sdev);

	switch (h->tpgs) {

	case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:

		sdev_printk(KERN_INFO, sdev,
@@ -642,7 +599,7 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) 
{

	int err;



	err = alua_std_inquiry(sdev, h);

	err = alua_check_tpgs(sdev, h);

	if (err != SCSI_DH_OK)

		goto out;

include/scsi/scsi_device.h

+5 −0
Original line number Diff line number Diff line
@@ -471,6 +471,11 @@ static inline int scsi_device_protection(struct scsi_device *sdev) 
	return sdev->scsi_level > SCSI_2 && sdev->inquiry[5] & (1<<0);

}



static inline int scsi_device_tpgs(struct scsi_device *sdev)

{

	return sdev->inquiry ? (sdev->inquiry[5] >> 4) & 0x3 : 0;

}



#define MODULE_ALIAS_SCSI_DEVICE(type) \

	MODULE_ALIAS("scsi:t-" __stringify(type) "*")

#define SCSI_DEVICE_MODALIAS_FMT "scsi:t-0x%02x"