Man page 9 : fcntl_getlease

fcntl_getlease - Enquire what lease is currently active

int fcntl_getlease(struct file *  filp );

filp
    the file

The value returned by this function will be one of (if no lease break is pending):

F_RDLCK to indicate a shared lease is held.

F_WRLCK to indicate an exclusive lease is held.

F_UNLCK to indicate no lease is held.

(if a lease break is pending):

F_RDLCK to indicate an exclusive lease needs to be changed to a shared lease (or removed).

F_UNLCK to indicate the lease needs to be removed.

sfr & willy disagree over whether F_INPROGRESS should be returned to userspace.