+(* A device with just a modified block size. *)
+class blocksize_overlay new_blocksize (dev : device) =
+object
+ inherit device
+ method name = dev#name
+ method size = dev#size
+ method read offset len = dev#read offset len
+ method blocksize = new_blocksize
+ method mapblock new_blk =
+ let orig_blk =
+ new_blk *^ Int64.of_int new_blocksize /^ Int64.of_int dev#blocksize in
+ dev#mapblock orig_blk
+end
+