Date: Mon, 26 Aug 2013 10:30:05 -0400 From: John Baldwin <jhb@freebsd.org> To: Ian Lepore <ian@freebsd.org> Cc: Yuri <yuri@rawbw.com>, John-Mark Gurney <jmg@funkthat.com>, Mateusz Guzik <mjguzik@gmail.com>, Roman Divacky <rdivacky@freebsd.org>, freebsd-current@freebsd.org Subject: Re: How to best overload the fileops ? Message-ID: <201308261030.05683.jhb@freebsd.org> In-Reply-To: <1377290165.1111.85.camel@revolution.hippie.lan> References: <521508F4.6030502@rawbw.com> <5217C0DC.8050107@rawbw.com> <1377290165.1111.85.camel@revolution.hippie.lan>
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On Friday, August 23, 2013 4:36:05 pm Ian Lepore wrote:
> On Fri, 2013-08-23 at 13:06 -0700, Yuri wrote:
> > On 08/23/2013 10:02, John Baldwin wrote:
> > > There is something similar: see devfs_ops_f in
sys/fs/devfs/devfs_vnops.c.
> >
> > devfs_ops_f is a local static fileops object for devfs. I don't see how
> > is this similar to our situation. devfs doesn't overload any other file
> > system, they are a file system on their own.
> >
>
> I think the point is that devfs_ops_f provides several devfs-specific
> methods and then "inherits" the rest by referencing the standard
> vn_whatever functions. Since John recommended that you expose the
> fo_whatever methods, I think he's suggesting you build your ops table by
> providing your own close method and fill in the rest of the table with
> the now-exposed kqueue ops methods.
>
> It's not as neat and clean as "class epollops : public kqueueops {...}"
> but it's probably not as bad as using clever macros to try to turn C
> into a sort of C++Lite.
Correct. Just use something like:
static struct fileops epollops = {
.fo_read = kqueue_read,
...
.fo_close = epoll_close,
...
}
--
John Baldwin
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