On 06/16/2017 10:44 AM, Martin K. Petersen wrote:

Jens,

quoted

We have a pwritev2(2) interface based on passing in flags. Add an
fcntl interface for querying these flags, and also for setting them
as well:

F_GET_WRITE_LIFE	Returns one of the valid type of write hints,
			like WRITE_HINT_MEDIUM.

F_SET_WRITE_LIFE	Pass in a WRITE_HINT_* type to set the
			write life time hint for this file/inode.
			Returns 0 on succes, -1 otherwise.

It seems like an overkill to have different fcntls for different
hints. And since we are expecting more, maybe these should be
F_{GET,SET}_HINT and then the individual flags can be
WRITE_LIFETIME_FOOBAR?

Otherwise OK with the fnctl approach.

OK, that's a useful suggestion. The hints are already of the
WRITE_HINT_* variant, so I don't think we need to change that. I'll
change the name.

-- 
Jens Axboe