[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: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 6fec9fe..4326778 100644 (file)
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -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;
 

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d371c3c..f751d37 100644 (file)
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -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"