[SCSI] megaraid: Add support for change_queue_depth

Adds support for change_queue_depth so that device
queue depth can be changed at runtime through sysfs.

Signed-off-by: <brking@charter.net>
Acked-by: NSeokmann Ju <seokmann.ju@lsil.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/megaraid/megaraid_mbox.c

@@ -330,6 +330,21 @@ static struct device_attribute *megaraid_sdev_attrs[] = {
 	NULL,
 };
 
+/**
+ * megaraid_change_queue_depth - Change the device's queue depth
+ * @sdev:	scsi device struct
+ * @qdepth:	depth to set
+ *
+ * Return value:
+ * 	actual depth set
+ **/
+static int megaraid_change_queue_depth(struct scsi_device *sdev, int qdepth)
+{
+	if (qdepth > MBOX_MAX_SCSI_CMDS)
+		qdepth = MBOX_MAX_SCSI_CMDS;
+	scsi_adjust_queue_depth(sdev, 0, qdepth);
+	return sdev->queue_depth;
+}
 
 /*
  * Scsi host template for megaraid unified driver
@@ -343,6 +358,7 @@ static struct scsi_host_template megaraid_template_g = {
 	.eh_device_reset_handler	= megaraid_reset_handler,
 	.eh_bus_reset_handler		= megaraid_reset_handler,
 	.eh_host_reset_handler		= megaraid_reset_handler,
+	.change_queue_depth		= megaraid_change_queue_depth,
 	.use_clustering			= ENABLE_CLUSTERING,
 	.sdev_attrs			= megaraid_sdev_attrs,
 	.shost_attrs			= megaraid_shost_attrs,