This patch provides set_params interface for scsi_dh_alua handler.
Handler expects only one parameter to set the flag ALUA_OPTIMIZE_STPG.
This flag is used to optimize the STPG behaviour. There is no change in
behaviour by default.
For example, to set the flag pass the following parameters from multipath.conf
hardware_handler "2 alua 1"
Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
--- linux-3.3-rc6/drivers/scsi/device_handler/scsi_dh_alua.c.orig 2012-03-12 13:22:16.000000000 -0500
+++ linux-3.3-rc6/drivers/scsi/device_handler/scsi_dh_alua.c 2012-03-12 13:22:49.000000000 -0500
@@ -55,11 +55,15 @@
#define ALUA_FAILOVER_TIMEOUT (60 * HZ)
#define ALUA_FAILOVER_RETRIES 5
+/* flags passed from user level */
+#define ALUA_OPTIMIZE_STPG 1
+
struct alua_dh_data {
int group_id;
int rel_port;
int tpgs;
int state;
+ unsigned flags; /* used for optimizing STPG */
unsigned char inq[ALUA_INQUIRY_SIZE];
unsigned char *buff;
int bufflen;
@@ -621,6 +625,37 @@ static int alua_initialize(struct scsi_d
out:
return err;
}
+/*
+ * alua_set_params - set/unset the optimize flag
+ * @sdev: device on the path to be activated
+ * params - parameters in the following format
+ * "no_of_params\0param1\0param2\0param3\0...\0"
+ * For example, to set the flag pass the following parameters
+ * from multipath.conf
+ * hardware_handler "2 alua 1"
+ */
+static int alua_set_params(struct scsi_device *sdev, const char *params)
+{
+ struct alua_dh_data *h = get_alua_data(sdev);
+ unsigned int optimize = 0, argc;
+ const char *p = params;
+ int result = SCSI_DH_OK;
+
+ if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
+ return -EINVAL;
+
+ while (*p++)
+ ;
+ if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
+ return -EINVAL;
+
+ if (optimize)
+ h->flags |= ALUA_OPTIMIZE_STPG;
+ else
+ h->flags &= ~ALUA_OPTIMIZE_STPG;
+
+ return result;
+}
/*
* alua_activate - activate a path
@@ -698,6 +733,7 @@ static struct scsi_device_handler alua_d
.prep_fn = alua_prep_fn,
.check_sense = alua_check_sense,
.activate = alua_activate,
+ .set_params = alua_set_params,
.match = alua_match,
};
--
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