The attached patch further changes the nommu stuff previously changed. These
new changes do the following:

 (0) Some additional variables have been defined to make nommu even compile.

 (1) Get rid of the alternate vm_area_struct. The nommu mmap now uses the
     normal one. There's a refcount field added to the normal one, contingent
     on !CONFIG_MMU.

 (2) vm_rb is now used to keep track of the VMAs in an rbtree rather than
     adding a separate list.

 (3) mm_tblock_struct is now vm_list_struct.

 (4) put_vma() now calls vma->vm_ops->close() if available on nommu.

 (5) A dummy generic_file_vm_ops has been provided. It does nothing, but
     permits tiny-shmem to compile.

     tiny-shmem and ramfs still need attention, such that files contained
     therein can be mmapped shared-writably to some extent on nommu.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>