[PATCH] NOMMU: Set BDI capabilities for /dev/mem and /dev/kmem

Set the backing device info capabilities for /dev/mem and /dev/kmem to
permit direct sharing under no-MMU conditions and full mapping capabilities
under MMU conditions.  Make the BDI used by these available to all directly
mappable character devices.

Also comment the capabilities for /dev/zero.

[akpm@osdl.org: ifdef reductions]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/cdev.h b/include/linux/cdev.h
index 2216638..ee5f53f 100644
--- a/include/linux/cdev.h
+++ b/include/linux/cdev.h
@@ -23,5 +23,7 @@
 
 void cd_forget(struct inode *);
 
+extern struct backing_dev_info directly_mappable_cdev_bdi;
+
 #endif
 #endif