[Linux-cachefs] An incorrect assumption over radix_tree_tag_get()

[Nick Piggin]

On Tue, Apr 06, 2010 at 05:19:49PM +0100, David Howells wrote:
> 
> Hi,
> 
> I think I've made a bad assumption over my usage of radix_tree_tag_get() in
> fs/fscache/page.c.
> 
> I've assumed that radix_tree_tag_get() is protected from radix_tree_tag_set()
> and radix_tree_tag_clear() by the RCU read lock.  However, now I'm not so
> sure.  I think it's only protected against removal of part of the tree.
> 
> Can you confirm?

It is safe. Synchronization requirements for using the radix tree API
are documented.