vfs: make first argument of dir_context.actor typed

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/exportfs/expfs.c

@@ -241,10 +241,11 @@ struct getdents_callback {
  * A rather strange filldir function to capture
  * the name matching the specified inode number.
  */
-static int filldir_one(void * __buf, const char * name, int len,
+static int filldir_one(struct dir_context *ctx, const char *name, int len,
 			loff_t pos, u64 ino, unsigned int d_type)
 {
-	struct getdents_callback *buf = __buf;
+	struct getdents_callback *buf =
+		container_of(ctx, struct getdents_callback, ctx);
 	int result = 0;
 
 	buf->sequence++;