locks: add new struct list_head to struct file_lock

...that we can use to queue file_locks to per-ctx list_heads. Go ahead
and convert locks_delete_lock and locks_dispose_list to use it instead
of the fl_block list.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Acked-by: Christoph Hellwig <hch@lst.de>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 42efe13..cd68181 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -934,6 +934,7 @@
  */
 struct file_lock {
 	struct file_lock *fl_next;	/* singly linked list for this inode  */
+	struct list_head fl_list;	/* link into file_lock_context */
 	struct hlist_node fl_link;	/* node in global lists */
 	struct list_head fl_block;	/* circular list of blocked processes */
 	fl_owner_t fl_owner;