diff --git a/functional-tests/block-cache.scm b/functional-tests/block-cache.scm
new file mode 100644
index 0000000..6b0dfc8
--- /dev/null
+++ b/functional-tests/block-cache.scm
@@ -0,0 +1,83 @@
+(library
+  (block-cache)
+  (exports)
+  (imports (chezscheme))
+
+  (define (cache-open path block-size nr-cache-blocks)
+    ...
+    )
+
+  (define (cache-read-lock cache index)
+    
+    )
+
+  (define (cache-write-lock cache index))
+  (define (cache-zero-lock cache index))
+
+  ;; The super block is the one that should be written last.  Unlocking this
+  ;; block triggers the following events:
+  ;;
+  ;; i)  synchronous write of all dirty blocks _except_ the superblock.
+  ;;
+  ;; ii)  synchronous write of superblock
+  ;;
+  ;; If any locks are held at the time of the superblock being unlocked then an
+  ;; error will be raised.
+  (define (cache-superblock-lock cache index))
+  (define (cache-superblock-zero))
+
+  (define (cache-unlock b)
+    )
+
+  (define-syntax with-block
+    (syntax-rules ()
+      ((_ (var b) body ...)
+       (let ((var b))
+        (dynamic-wind
+         (lambda () #f)
+         (lambda () body ...)
+         (lambda () (block-put var)))))))
+
+  ;;--------------------------------------------
+
+  (define-record-type ro-spine (fields cache parent child))
+
+  (define (ro-spine-begin cache)
+    (make-ro-spine cache #f #f))
+
+  (define (ro-spine-end spine)
+    (define (unlock bl)
+      (if bl (cache-unlock) #f))
+
+    (unlock (ro-spine-parent spine))
+    (unlock (ro-spine-child spine))
+    (ro-spine-parent-set! spine #f)
+    (ro-spind-child-set! spine #f))
+
+  (define (ro-spine-step spine index)
+    (define (push b)
+      (cond
+        ((ro-spine-child spine)
+         (let ((grandparent (ro-spine-parent spine)))
+          (ro-spine-parent-set! spine (ro-spine-child spine))
+          (ro-spine-child-set! spine b)))
+        ((ro-spine-parent spine)
+         (ro-spine-child-set! spine b))
+        (else
+          (ro-spine-parent-set! spine b))))
+
+    (push (cache-read-lock (ro-spine-cache spine) index)))
+
+  (define-syntax with-ro-spine
+    (syntax-rules ()
+      ((_ (n cache) body ...)
+
+       (let ((n (ro-spine-begin cache)))
+        (dynamic-wind
+         (lambda () #f)
+         (lambda () body ...)
+         (lambda () (ro-spine-end)))))))
+
+  )
+
+
diff --git a/functional-tests/block-io.scm b/functional-tests/block-io.scm
index dc873a2..7cf0625 100644
--- a/functional-tests/block-io.scm
+++ b/functional-tests/block-io.scm
@@ -22,11 +22,12 @@
 
   (define-syntax with-metadata
     (syntax-rules ()
-      ((_ (port path) body ...) (let ((port (open-metadata path)))
-                                 (dynamic-wind
-                                   (lambda () #f)
-                                   (lambda () body ...)
-                                   (lambda () (close-port port)))))))
+      ((_ (port path) body ...)
+       (let ((port (open-metadata path)))
+        (dynamic-wind
+          (lambda () #f)
+          (lambda () body ...)
+          (lambda () (close-port port)))))))
 
   ;; FIXME: return our own condition?
   (define (io-error msg)
diff --git a/functional-tests/btree.scm b/functional-tests/btree.scm
index e2c0f26..a947ca4 100644
--- a/functional-tests/btree.scm
+++ b/functional-tests/btree.scm
@@ -89,20 +89,15 @@
     (let ((dev (btree-dev tree))
           (vt (btree-value-type tree)))
 
-      (define (lookup root fail-k)
-        (let loop ((root root))
-         (let* ((node (read-block dev root))
-                (header (node-header-unpack node 0))
-                (index (lower-bound node header key)))
-           (if (internal-node? header)
-               (loop (value-at header node index le64-type))
-               (if (= key (key-at node index))
-                   (value-at header node index vt)
-                   (fail-k default))))))
-
-      (call/cc
-        (lambda (fail-k)
-          (lookup (btree-root tree) fail-k)))))
+      (let loop ((root (btree-root tree)))
+       (let* ((node (read-block dev root))
+              (header (node-header-unpack node 0))
+              (index (lower-bound node header key)))
+         (if (internal-node? header)
+             (loop (value-at header node index le64-type))
+             (if (= key (key-at node index))
+                 (value-at header node index vt)
+                 default))))))
 
   ;;;;----------------------------------------------
   ;;;; Walking the btree
diff --git a/functional-tests/mapping-tree.scm b/functional-tests/mapping-tree.scm
index 1f28e7a..00028a1 100644
--- a/functional-tests/mapping-tree.scm
+++ b/functional-tests/mapping-tree.scm
@@ -7,7 +7,6 @@
 
   (import (btree)
           (chezscheme)
-          (binary-format)
           (srfi s8 receive))
 
   (define-record-type mapping-tree (fields dev-tree))
@@ -15,6 +14,13 @@
   (define (mapping-tree-open dev root)
     (make-mapping-tree (btree-open le64-type dev root)))
 
+  ;; (values <block> <time>)
+  (define time-mask (- (fxsll 1 24) 1))
+
+  (define (unpack-block-time bt)
+    (values (fxsrl bt 24) (fxlogand bt time-mask)))
+
+  ;; FIXME: unpack the block time
   (define (mapping-tree-lookup mtree dev-id vblock default)
     (let* ((unique (gensym))
            (dev-tree (mapping-tree-dev-tree mtree))
@@ -23,12 +29,6 @@
          default
          (btree-lookup (btree-open le64-type (btree-dev dev-tree) root2) vblock default))))
 
-  ;; (values <block> <time>)
-  (define time-mask (- (fxsll 1 24) 1))
-
-  (define (unpack-block-time bt)
-    (values (fxsrl bt 24) (fxlogand bt time-mask)))
-
   ;;; Visits every entry in the mapping tree calling (fn dev-id vblock pblock time).
   (define (mapping-tree-each mtree fn)
     (let ((dev-tree (mapping-tree-dev-tree mtree)))