Re: [Lsf-pc] [LSF/MM TOPIC] [LSF/MM ATTEND] FS Management Interfaces

[Jan Kara <jack@suse.cz>]

Hi,

On Tue 10-01-17 09:44:59, Steven Whitehouse wrote:
> I had originally thought about calling the proposal "kernel/userland
> interface", however that seemed a bit vague and management interfaces seems
> like a better title since it is I hope a bit clearer of the kind of thing
> that I'm thinking about in this case.
> 
> There are a number of possible sub-topics and I hope that I might find a few
> more before LSF too. One is that of space management (we have statfs, but
> currently no notifications for thresholds crossed etc., so everything is
> polled. That is ok sometimes, but statfs can be expensive in the case of
> distributed filesystems, if 100% accurate. We could just have ENOSPC
> notifications for 100% full, or something more generic), another is state
> transitions (is the fs running normally, or has it gone read
> only/withdrawn/etc due to I/O errors?) and a further topic would be working
> towards a common interface for fs statistics (at the moment each fs defines
> their own interface). One potential implementation, at least for the first
> two sub-topics, would be to use something along the lines of the quota
> netlink interface, but since few ideas survive first contact with the
> community at large, I'm throwing this out for further discussion and
> feedback on whether this approach is considered the right way to go.
> 
> Assuming the topic is accepted, my intention would be to gather together
> some additional sub-topics relating to fs management to go along with those
> I mentioned above, and I'd be very interested to hear of any other issues
> that could be usefully added to the list for discussion.

So this topic came up last year and probably the year before as well (heh,
I can even find some patches from 2011 [1]). I think the latest attempt at
what you suggest was here [2]. So clearly there's some interest in these
interfaces but not enough to actually drive anything to completion. So for
this topic to be useful, I think you need to go at least through the
patches in [2] and comments to them and have a concrete proposal that can
be discussed and some commitment (not necessarily from yourself) that
someone is going to devote time to implement it. Because generally nobody
seems to be opposed to the abstract idea but once it gets to the
implementation details, it is non-trivial to get some wider agreement
(statx anybody? ;)).

								Honza

[1] https://lkml.org/lkml/2011/8/18/170
[2] https://lkml.org/lkml/2015/6/16/456
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR