The op argument will be either LOCK_SH, LOCK_EX or LOCK_UN
Nonblocking requests will be indicated by ORing LOCK_NB to
the above operations
For more information see the flock(2) manual page.
Additionally fi->owner will be set to a value unique to
this open file. This same value will be supplied to
->release() when the file is released.
Note: if this method is not implemented, the kernel will still
allow file locking to work locally. Hence it is only
interesting for network filesystems and similar.
Perform BSD file locking operation
The op argument will be either LOCK_SH, LOCK_EX or LOCK_UN
Nonblocking requests will be indicated by ORing LOCK_NB to the above operations
For more information see the flock(2) manual page.
Additionally fi->owner will be set to a value unique to this open file. This same value will be supplied to ->release() when the file is released.
Note: if this method is not implemented, the kernel will still allow file locking to work locally. Hence it is only interesting for network filesystems and similar.
Introduced in version 2.9