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From: "Robert N. M. Watson" <rwatson@freebsd.org>
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To: Mikolaj Golub <trociny@freebsd.org>
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Cc: Kostik Belousov <kib@freebsd.org>, freebsd-arch@freebsd.org
Subject: Re: unix domain sockets on nullfs(5)
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On 12 Jan 2012, at 21:17, Mikolaj Golub wrote:

> If we agree to have only the new behavior then nullfs won't need =
modification
> at all, it will work as expected automatically. The patch could be =
(with updated
> locking for the connect case):
>=20
> http://people.freebsd.org/~trociny/VOP_UNP.1.patch

Greatly simplified.

> --- sys/kern/uipc_usrreq.c	(revision 229979)
> +++ sys/kern/uipc_usrreq.c	(working copy)
> @@ -542,7 +542,7 @@
> =20
>  	UNP_LINK_WLOCK();
>  	UNP_PCB_LOCK(unp);
> -	vp->v_socket =3D unp->unp_socket;
> +	VOP_UNPBIND(vp, unp->unp_socket);
>  	unp->unp_vnode =3D vp;
>  	unp->unp_addr =3D soun;
>  	unp->unp_flags &=3D ~UNP_BINDING;


I still find myself worried by the fact that unp->unp_vnode points at =
the nullfs vnode rather than the underlying vnode, but haven't yet =
managed to identify any actual bugs that would result. I'll continue =
pondering it over the weekend :-).

Robert=