Does anyone know why the variable passed into yaffs_addr_to_chunk() 
through the chunk_out parameter needs to be incremented by 1 afterwards?

It looks like every place this function is called in yaffs_guts.c and 
yaffs_verify.c, the "chunk" is always incremented.  Seems like 
yaffs_addr_to_chunk() should do that for us... as if it's giving the 
"wrong" answer/chunk.