* Fixed (or rather, worked around) a deadlock in the VM: when a file was

resized but still had dirty pages to be written back, 
  vm_cache_resize() (which is called with the inode lock being held)
  deadlocked with the page writer.
* Now, I reintroduced busy_writing: it'll be set by everything that
  writes back pages (vm_page_write_modified(), and the page writer),
  and will be checked for in vm_cache_resize() - other functions are not
  affected for now, AFAICT.
* vm_cache_resize() will clear that flag, and the writer will check it
  again after it wrote back the page (which will fail when it's outside
  the file bounds), and if it's cleared, it will get rid of the page
  (if the file has been resized again in the mean time, writing it will
  succeed then, and we'll keep the page around).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23334 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vm_types.h

@@ -100,6 +100,7 @@ struct vm_page {
 
 	uint8				is_cleared : 1;
 		// is currently only used in vm_page_allocate_page_run()
+	uint8				busy_writing : 1;
 
 	uint16				wired_count;
 	int8				usage_count;