[PATCH 05/11] scsi: core: Add support for reserved tags

@@ -1916,6 +1916,7 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
 {
 	unsigned int cmd_size, sgl_size;
 	struct blk_mq_tag_set *tag_set = &shost->tag_set;
+	unsigned int reserved_tags = shost->hostt->reserved_tags;
 
 	sgl_size = max_t(unsigned int, sizeof(struct scatterlist),
 				scsi_mq_inline_sgl_size(shost));

@@ -1931,7 +1932,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost)
 		tag_set->ops = &scsi_mq_ops_no_commit;
 	tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
 	tag_set->nr_maps = shost->nr_maps ? : 1;
-	tag_set->queue_depth = shost->can_queue;
+	tag_set->queue_depth = shost->can_queue + reserved_tags;
+	tag_set->reserved_tags = reserved_tags;
 	tag_set->cmd_size = cmd_size;
 	tag_set->numa_node = NUMA_NO_NODE;
 	tag_set->flags = BLK_MQ_F_SHOULD_MERGE;

@@ -367,10 +367,17 @@ struct scsi_host_template {
 	/*
 	 * This determines if we will use a non-interrupt driven
 	 * or an interrupt driven scheme.  It is set to the maximum number
-	 * of simultaneous commands a single hw queue in HBA will accept.
+	 * of simultaneous commands a single hw queue in HBA will accept. Does
+	 * not include @reserved_tags.
 	 */
 	int can_queue;
 
+	/*
+	 * Number of tags to reserve. A reserved tag can be allocated by passing
+	 * the BLK_MQ_REQ_RESERVED flag to blk_get_request().
+	 */
+	unsigned reserved_tags;
+
 	/*
 	 * In many instances, especially where disconnect / reconnect are
 	 * supported, our host also has an ID on the SCSI bus.  If this is