suse man page for posix_lock_file

POSIX_LOCK_FILE(9)						   The Linux VFS						POSIX_LOCK_FILE(9)

NAME
       posix_lock_file - Apply a POSIX-style lock to a file

SYNOPSIS
       int posix_lock_file(struct file * filp, struct file_lock * fl, struct file_lock * conflock);

ARGUMENTS
       filp
	   The file to apply the lock to

       fl
	   The lock to be applied

       conflock
	   Place to return a copy of the conflicting lock, if found.

DESCRIPTION
       Add a POSIX style lock to a file. We merge adjacent & overlapping locks whenever possible. POSIX locks are sorted by owner task, then by
       starting address

       Note that if called with an FL_EXISTS argument, the caller may determine whether or not a lock was successfully freed by testing the return
       value for -ENOENT.

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010							POSIX_LOCK_FILE(9)