[LogFS] add new flash file system

This is a new flash file system. See
Documentation/filesystems/logfs.txt

Signed-off-by: Joern Engel <joern@logfs.org>
diff --git a/include/linux/btree-128.h b/include/linux/btree-128.h
new file mode 100644
index 0000000..0b3414c
--- /dev/null
+++ b/include/linux/btree-128.h
@@ -0,0 +1,109 @@
+extern struct btree_geo btree_geo128;
+
+struct btree_head128 { struct btree_head h; };
+
+static inline void btree_init_mempool128(struct btree_head128 *head,
+					 mempool_t *mempool)
+{
+	btree_init_mempool(&head->h, mempool);
+}
+
+static inline int btree_init128(struct btree_head128 *head)
+{
+	return btree_init(&head->h);
+}
+
+static inline void btree_destroy128(struct btree_head128 *head)
+{
+	btree_destroy(&head->h);
+}
+
+static inline void *btree_lookup128(struct btree_head128 *head, u64 k1, u64 k2)
+{
+	u64 key[2] = {k1, k2};
+	return btree_lookup(&head->h, &btree_geo128, (unsigned long *)&key);
+}
+
+static inline void *btree_get_prev128(struct btree_head128 *head,
+				      u64 *k1, u64 *k2)
+{
+	u64 key[2] = {*k1, *k2};
+	void *val;
+
+	val = btree_get_prev(&head->h, &btree_geo128,
+			     (unsigned long *)&key);
+	*k1 = key[0];
+	*k2 = key[1];
+	return val;
+}
+
+static inline int btree_insert128(struct btree_head128 *head, u64 k1, u64 k2,
+				  void *val, gfp_t gfp)
+{
+	u64 key[2] = {k1, k2};
+	return btree_insert(&head->h, &btree_geo128,
+			    (unsigned long *)&key, val, gfp);
+}
+
+static inline int btree_update128(struct btree_head128 *head, u64 k1, u64 k2,
+				  void *val)
+{
+	u64 key[2] = {k1, k2};
+	return btree_update(&head->h, &btree_geo128,
+			    (unsigned long *)&key, val);
+}
+
+static inline void *btree_remove128(struct btree_head128 *head, u64 k1, u64 k2)
+{
+	u64 key[2] = {k1, k2};
+	return btree_remove(&head->h, &btree_geo128, (unsigned long *)&key);
+}
+
+static inline void *btree_last128(struct btree_head128 *head, u64 *k1, u64 *k2)
+{
+	u64 key[2];
+	void *val;
+
+	val = btree_last(&head->h, &btree_geo128, (unsigned long *)&key[0]);
+	if (val) {
+		*k1 = key[0];
+		*k2 = key[1];
+	}
+
+	return val;
+}
+
+static inline int btree_merge128(struct btree_head128 *target,
+				 struct btree_head128 *victim,
+				 gfp_t gfp)
+{
+	return btree_merge(&target->h, &victim->h, &btree_geo128, gfp);
+}
+
+void visitor128(void *elem, unsigned long opaque, unsigned long *__key,
+		size_t index, void *__func);
+
+typedef void (*visitor128_t)(void *elem, unsigned long opaque,
+			     u64 key1, u64 key2, size_t index);
+
+static inline size_t btree_visitor128(struct btree_head128 *head,
+				      unsigned long opaque,
+				      visitor128_t func2)
+{
+	return btree_visitor(&head->h, &btree_geo128, opaque,
+			     visitor128, func2);
+}
+
+static inline size_t btree_grim_visitor128(struct btree_head128 *head,
+					   unsigned long opaque,
+					   visitor128_t func2)
+{
+	return btree_grim_visitor(&head->h, &btree_geo128, opaque,
+				  visitor128, func2);
+}
+
+#define btree_for_each_safe128(head, k1, k2, val)	\
+	for (val = btree_last128(head, &k1, &k2);	\
+	     val;					\
+	     val = btree_get_prev128(head, &k1, &k2))
+