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Date: Tue, 4 Jun 2019 01:54:42 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: Alan Somers <asomers@freebsd.org>
Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>
Subject: Re: How to VOP_RECLAIM on demand?
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On Mon, Jun 03, 2019 at 04:27:26PM -0600, Alan Somers wrote:
> On Mon, Jun 3, 2019 at 3:15 PM Konstantin Belousov <kostikbel@gmail.com> wrote:
> >
> > On Mon, Jun 03, 2019 at 02:38:11PM -0600, Alan Somers wrote:
> > > It would be useful if I could trigger VOP_RECLAIM on demand for a
> > > certain file or pathname.  There are some edge cases in fusefs that I
> > > can't test otherwise.  But I don't see any way to do it.  Is such a
> > > thing possible?  Would it be worth adding a special syscall for this
> > > purpose?  It could be guarded with INVARIANTS so it wouldn't affect
> > > production builds.
> >
> > Look at revoke(2) and VOP_REVOKE().  It is only implemented and used
> > for devfs tty nodes.
> 
> I don't understand how that would help.  What does VOP_REVOKE have in
> common with VOP_RECLAIM?
Sane implementation of VOP_REVOKE for a filesystem that does not do tricks
at files level (think devfs) is mostly {vgone(vp);}.