block: split tag and sysfs handling from blk-core.c

Seperates the tag and sysfs handling from ll_rw_blk.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk.h

@@ -0,0 +1,29 @@
+#ifndef BLK_INTERNAL_H
+#define BLK_INTERNAL_H
+
+extern struct kmem_cache *blk_requestq_cachep;
+extern struct kobj_type blk_queue_ktype;
+
+void __blk_queue_free_tags(struct request_queue *q);
+
+void blk_queue_congestion_threshold(struct request_queue *q);
+
+/*
+ * Return the threshold (number of used requests) at which the queue is
+ * considered to be congested.  It include a little hysteresis to keep the
+ * context switch rate down.
+ */
+static inline int queue_congestion_on_threshold(struct request_queue *q)
+{
+	return q->nr_congestion_on;
+}
+
+/*
+ * The threshold at which a queue is considered to be uncongested
+ */
+static inline int queue_congestion_off_threshold(struct request_queue *q)
+{
+	return q->nr_congestion_off;
+}
+
+#endif