Another work-in-progress towards having extra structures per mapping per page:

* vm_area and vm_page now have a new field "mappings" where they will store lists
  of vm_page_mapping structures. vm_page::ref_count is gone, as it's no longer
  needed (it was never updated correctly, anyway).
* vm_caches now have a type field, ie. CACHE_TYPE_RAM for anonymous areas - this
  makes the stores a bit less independent, but is quite handy in several places.
* Added new vm_map_page() and vm_unmap_pages() functions to be used whenever you
  map in or unmap pages into/from an area. They don't do much more than handling
  vm_page::wired_count correctly right now, though (ie. B_LAZY_LOCK is now working
  as expected as well).
* Moved the device fault handler to vm_map_physical_memory(); it was not really
  used as a fault handler, anyway.
* Didn't notice Ingo's changes to the I/O space region broke lock_memory(). It
  now checks the type of the area that contains the memory, and doesn't lock
  anymore if not needed which solves the problem in a platform independent way.
* Implemented lock_memory() and unlock_memory() for real: they now change the
  vm_page::wired_count member to identify pages that shouldn't be paged out.
* vm_area_for() now uses vm_area_lookup() internally.
* Fixed various potential overflow conditions with areas that reach 0xffffffff.
* Creating anonymous areas with B_FULL_LOCK no longer causes vm_soft_fault()
  to be called, instead, the pages are allocated and mapped (via vm_map_page())
  directly.
* Removed the _vm_ prefix for create_area_struct() and create_reserved_area_struct().
* Fixed a bug in vm_page_write_modified() that would not have enqueued pages that
  failed to be written to the modified queue again when needed.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20251 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vm.h

@@ -60,10 +60,11 @@ area_id vm_clone_area(team_id team, const char *name, void **address,
 status_t vm_delete_area(team_id aid, area_id id);
 status_t vm_create_vnode_cache(void *vnode, vm_cache_ref **_cacheRef);
 vm_area *vm_area_lookup(vm_address_space *addressSpace, addr_t address);
-
 status_t vm_set_area_memory_type(area_id id, addr_t physicalBase, uint32 type);
-
 status_t vm_get_page_mapping(team_id team, addr_t vaddr, addr_t *paddr);
+status_t vm_unmap_pages(vm_area *area, addr_t base, size_t length);
+status_t vm_map_page(vm_area *area, vm_page *page, addr_t address,
+			uint32 protection);
 status_t vm_get_physical_page(addr_t paddr, addr_t *vaddr, uint32 flags);
 status_t vm_put_physical_page(addr_t vaddr);