Re: NFSv4 file lock reporting interface request

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Aug 07, 2018 at 05:16:24PM -0400, J. Bruce Fields wrote:
> On Tue, Aug 07, 2018 at 04:05:42PM -0500, Tom Tucker wrote:
> > FWIW, I don't think dtrace does/did what NASA is asking for, but
> > that's really irrelevant. The locks in NFSv4 are application
> > specific locks, not generic kernel locks, so a service looking for
> > spinlocks, mutexes, etc... wouldn't really be helpful I don't
> > think.  However implementing a /sys/class, debugfs thingy that
> > dumped the nfsv4 locks held is fairly simple, although I would think
> > there are security implications.
> 
> We already have /proc/locks for locks taken by regular applications, it
> just misses locks from nfsd.
> 
> We could extend that.  But /proc/locks has some other problems and best
> is probably to make a list of those and make sure we address them all at
> once.  It's a potential woodshedding exercise.

(Um, bikeshedding, bikeshedding.  Woodshedding is an entirely different
thing....)

--b.

> I haven't done any work
> on it.
> 
> Alternatively I guess we could make a separate interface just for file
> locks held by knfsd.
> 
> --b.