__get_lease - revoke all outstanding leases on file
int __get_lease (struct inode *inode, unsigned int mode);
inode the inode of the file to return mode the open mode (read or write)
get_lease (inlined for speed) has checked there already is a lease on this file. Leases are broken on a call to open or truncate. This function can sleep unless you specified O_NONBLOCK to your open.