locks: typedef fl_owner_t to void *

fl_owner_t is a cookie that can store all kinds of different pointers,
so don't pretends it points to a file structure.

For now just change the typedef, but as a follow on this will allow
to get rids of lots of casts and eventually the typedef itself.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJeff Layton <jlayton@primarydata.com>

include/linux/fs.h

@@ -833,7 +833,7 @@ static inline struct file *get_file(struct file *f)
  *
  * Lockd stuffs a "host" pointer into this.
  */
-typedef struct files_struct *fl_owner_t;
+typedef void *fl_owner_t;
 
 struct file_lock_operations {
 	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);