fscache: use appropriate radix tree accessors

Don't open-code accesses to data structure internals.

Link: http://lkml.kernel.org/r/20180313132639.17387-7-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fscache/cookie.c

@@ -832,7 +832,7 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
 	/* Clear pointers back to the netfs */
 	cookie->netfs_data	= NULL;
 	cookie->def		= NULL;
-	BUG_ON(cookie->stores.rnode);
+	BUG_ON(!radix_tree_empty(&cookie->stores));
 
 	if (cookie->parent) {
 		ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);

fs/fscache/object.c

@@ -973,7 +973,7 @@ static const struct fscache_state *_fscache_invalidate_object(struct fscache_obj
 	 * retire the object instead.
 	 */
 	if (!fscache_use_cookie(object)) {
-		ASSERT(object->cookie->stores.rnode == NULL);
+		ASSERT(radix_tree_empty(&object->cookie->stores));
 		set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
 		_leave(" [no cookie]");
 		return transit_to(KILL_OBJECT);