esp_scsi: make number of tags configurable

Add a field 'num_tags' to the esp structure to allow drivers
to overwrite the number of avialable tags if required.
Default is ESP_DEFAULT_TAGS.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/esp_scsi.c

@@ -2317,6 +2317,10 @@ int scsi_esp_register(struct esp *esp, struct device *dev)
 	static int instance;
 	int err;
 
+	if (!esp->num_tags)
+		esp->num_tags = ESP_DEFAULT_TAGS;
+	else if (esp->num_tags >= ESP_MAX_TAG)
+		esp->num_tags = ESP_MAX_TAG - 1;
 	esp->host->transportt = esp_transport_template;
 	esp->host->max_lun = ESP_MAX_LUN;
 	esp->host->cmd_per_lun = 2;
@@ -2403,12 +2407,8 @@ static int esp_slave_configure(struct scsi_device *dev)
 	struct esp *esp = shost_priv(dev->host);
 	struct esp_target_data *tp = &esp->target[dev->id];
 
-	if (dev->tagged_supported) {
-		/* XXX make this configurable somehow XXX */
-		int goal_tags = min(ESP_DEFAULT_TAGS, ESP_MAX_TAG);
-
-		scsi_change_queue_depth(dev, goal_tags);
-	}
+	if (dev->tagged_supported)
+		scsi_change_queue_depth(dev, esp->num_tags);
 
 	tp->flags |= ESP_TGT_DISCONNECT;
 

drivers/scsi/esp_scsi.h

@@ -283,7 +283,6 @@ struct esp_cmd_entry {
 	struct completion	*eh_done;
 };
 
-/* XXX make this configurable somehow XXX */
 #define ESP_DEFAULT_TAGS	16
 
 #define ESP_MAX_TARGET		16
@@ -445,7 +444,7 @@ struct esp {
 	u8			prev_soff;
 	u8			prev_stp;
 	u8			prev_cfg3;
-	u8			__pad;
+	u8			num_tags;
 
 	struct list_head	esp_cmd_pool;