locks: plumb a "priv" pointer into the setlease routines

In later patches, we're going to add a new lock_manager_operation to
finish setting up the lease while still holding the i_lock.  To do
this, we'll need to pass a little bit of info in the fcntl setlease
case (primarily an fasync structure). Plumb the extra pointer into
there in advance of that.

We declare this pointer as a void ** to make it clear that this is
private info, and that the caller isn't required to set this unless
the lm_setup specifically requires it.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Documentation/filesystems/Locking

@@ -464,7 +464,7 @@ prototypes:
 			size_t, unsigned int);
 	ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *,
 			size_t, unsigned int);
-	int (*setlease)(struct file *, long, struct file_lock **);
+	int (*setlease)(struct file *, long, struct file_lock **, void **);
 	long (*fallocate)(struct file *, int, loff_t, loff_t);
 };
 

Documentation/filesystems/vfs.txt

@@ -826,7 +826,7 @@ struct file_operations {
 	int (*flock) (struct file *, int, struct file_lock *);
 	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, size_t, unsigned int);
 	ssize_t (*splice_read)(struct file *, struct pipe_inode_info *, size_t, unsigned int);
-	int (*setlease)(struct file *, long arg, struct file_lock **);
+	int (*setlease)(struct file *, long arg, struct file_lock **, void **);
 	long (*fallocate)(struct file *, int mode, loff_t offset, loff_t len);
 	int (*show_fdinfo)(struct seq_file *m, struct file *f);
 };