switch touch_atime to struct path

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/cachefiles/namei.c

@@ -646,7 +646,8 @@ lookup_again:
 		 * (this is used to keep track of culling, and atimes are only
 		 * updated by read, write and readdir but not lookup or
 		 * open) */
-		touch_atime(cache->mnt, next);
+		path.dentry = next;
+		touch_atime(&path);
 	}
 
 	/* open a file interface onto a data file */