Apply a posix-style lock to a file
int posix_lock_file(struct file * filp, struct file_lock * fl, struct file_lock * conflock);
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.
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.