Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <CAK-6q+hS29yoTF4tKq+Xt3G=_PPDi9vmFVwGPmutbsQyD2i=CA@mail.gmail.com>
 <87pmwxsjxm.fsf@suse.com> <CAH2r5msMBZ5AYQcfK=-xrOASzVC0SgoHdPnyqEPRcfd-tzUstw@mail.gmail.com>
 <35352ef0-86ed-aaa5-4a49-b2b08dc3674d@samba.org> <CAK-6q+g3_9g++wQGbhzBhk2cp=0fb3aVL9GoAoYNPq6M4QnCdQ@mail.gmail.com>
 <20210608153349.0f02ba71@hermes.local> <20210609094818.7aaf21bd@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
In-Reply-To: <20210609094818.7aaf21bd@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
From:   Alexander Aring <aahringo@redhat.com>
Date:   Wed, 9 Jun 2021 14:44:40 -0400
Message-ID: <CAK-6q+g8gsot9s0z8HcdA91_QZjWqML4WTfkgcJuF_ea+kRGUQ@mail.gmail.com>
Subject: Re: quic in-kernel implementation?
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Stephen Hemminger <stephen@networkplumber.org>,
        Stefan Metzmacher <metze@samba.org>,
        Steve French <smfrench@gmail.com>,
        =?UTF-8?Q?Aur=C3=A9lien_Aptel?= <aaptel@suse.com>,
        Network Development <netdev@vger.kernel.org>,
        linux-nfs <linux-nfs@vger.kernel.org>,
        CIFS <linux-cifs@vger.kernel.org>,
        Leif Sahlberg <lsahlber@redhat.com>,
        Steven Whitehouse <swhiteho@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi,

On Wed, Jun 9, 2021 at 12:48 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Tue, 8 Jun 2021 15:33:49 -0700 Stephen Hemminger wrote:
> > On Tue, 8 Jun 2021 17:03:16 -0400
> > > > With having the fuse-like socket before it should be trivial to switch
> > > > between the implementations.
> > >
> > > So a good starting point would be to have such a "fuse-like socket"
> > > component? What about having a simple example for that at first
> > > without having quic involved. The kernel calls some POSIX-like socket
> > > interface which triggers a communication to a user space application.
> > > This user space application will then map everything to a user space
> > > generated socket. This would be a map from socket struct
> > > "proto/proto_ops" to user space and vice versa. The kernel application
> > > probably can use the kernel_FOO() (e.g. kernel_recvmsg()) socket api
> > > directly then. Exactly like "fuse" as you mentioned just for sockets.
> > >
> > > I think two veth interfaces can help to test something like that,
> > > either with a "fuse-like socket" on the other end or an user space
> > > application. Just doing a ping-pong example.
> > >
> > > Afterwards we can look at how to replace the user generated socket
> > > application with any $LIBQUIC e.g. msquic implementation as second
> > > step.
> >
> > Socket state management is complex and timers etc in userspace are hard.
>
> +1 seeing the struggles fuse causes in storage land "fuse for sockets"
> is not an exciting temporary solution IMHO..

What about an in-kernel sunrpc client which forwards "in-kernel proxy
socket syscall functions" to a user server who executes those on a
user socket? Does this sound like a better approach?
Sure there may be more problems, but maybe we could try it with
something simple at first to discover all those problems.

- Alex