anchor.diff:          :for directory :in (rest (pathname-directory pathname))
           :do (block do-files
                 (do-files (block offset) disk superblock bgdt inode-n
  -                        (error 'simple-file-error
  -                               :pathname pathname
  -                               :format-control "Directory ~A not found. ~S"
  -                               :format-arguments (list directory pathname))
  +                (error 'simple-file-error
  +                       :pathname pathname
  +                       :format-control "Directory ~A not found. ~S"
  +                       :format-arguments (list directory pathname))
                   (when (string= directory (linked-directory-entry-name (read-linked-directory-entry block offset)))
                     (setf inode-n (linked-directory-entry-inode (read-linked-directory-entry block offset)))
                     (return-from do-files t))))
  
positive.code:   (if (zerop n-indirection)
        (funcall fn (read-block disk superblock block-n))
        (iter (with i-block := (read-block disk superblock block-n))
          (for offset :from 0 :below (block-size-in-bytes disk superblock) :by 4)
          (for block-n := (sys.int::ub32ref/le i-block offset))
          (unless (and (zerop block-n))
            (follow-pointer disk superblock block-n fn (1- n-indirection))))))
  
  (defun do-file (fn disk superblock bgdt inode-n)
    (let* ((inode (read-inode disk superblock bgdt inode-n))
  
negative.code:               (iter (with block-group-size := (if (zerop (logand +incompat-64bit+
                                                                   (superblock-feature-incompat superblock)))
                                                    32 (superblock-desc-size superblock)))
                      (with n-octets := (* block-group-size (n-block-groups superblock)))
                      (with block := (read-block disk superblock 1
                                                 (/ n-octets
                                                    (mezzano.supervisor:disk-sector-size disk)
                                                    (block-size disk superblock))))
                      (for offset :from 0 :below n-octets :by block-group-size)
                      (collecting (read-block-group-descriptor superblock block offset)))))
  
  (defun read-block-bitmap (disk superblock bgds)
    (let ((n-blocks (if (zerop (logand +incompat-flex-bg+ (superblock-feature-incompat superblock)))
  