Date: Mon, 9 Mar 2009 22:52:00 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: nullfs: panic: vrele: negative ref cnt Message-ID: <20090309205200.GY41617@deviant.kiev.zoral.com.ua> In-Reply-To: <200903091642.25311.jhb@freebsd.org> References: <3a142e750903090615t63a594e8rbadd7f7231049180@mail.gmail.com> <200903091642.25311.jhb@freebsd.org>
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On Mon, Mar 09, 2009 at 04:42:25PM -0400, John Baldwin wrote:
> On Monday 09 March 2009 9:15:22 am Paul B. Mahol wrote:
> > Hi,
> > here is part of textdump:
> >=20
> > panic(c061db9e,0,c061cee6,88e,4,...) at panic+0x136
> > vrele(c4326d9c,0,c433fb5f,82,c060f3c7,...) at vrele+0x111
> > null_nodeget(c3fd4780,c4326d9c,c3ba8bf4,0,c3ba8be4,...) at null_nodeget=
+0xa0
> > null_bypass(c3ba8be0,c3f35a78,c3ba8c28) at null_bypass+0x141
> > VOP_VPTOCNP_APV(c4340240,c3ba8be0,c061bf01,387,c3cecc00,...) at
> > VOP_VPTOCNP_APV+0xb3
>=20
> Try this. null_bypass() can't handle VOP_VPTOCNP because VPTOCNP doesn't=
=20
> return a vnode that is locked and VREF'd, but just a vnode that is vhold(=
)'d. =20
> This patch attempts to give nullfs a VOP_VPTONCP() method which remaps th=
e=20
> directory vnode properly on return by locking the directory vnode while=
=20
> invoking null_nodeget().
>=20
> --- //depot/user/jhb/lock/fs/nullfs/null_vnops.c
> +++ /home/jhb/work/p4/lock/fs/nullfs/null_vnops.c
> @@ -722,6 +722,34 @@
> return VOP_VPTOFH(lvp, ap->a_fhp);
> }
> =20
> +static int
> +null_vptocnp(struct vop_vptocnp_args *ap)
> +{
> + struct vnode *lvp, *dvp;
> + int error;
> +
> + /*
> + * We can't use null_bypass() because 'dvp' is not returned
> + * locked. It is merely 'vhold()'ed.
> + */
> + lvp =3D NULLVPTOLOWERVP(ap->a_vp);
> + error =3D VOP_VPTOCNP(lvp, &dvp, ap->a_buf, ap->a_buflen);
> + if (error)
> + return (error);
> +
> + /*
> + * Map 'dvp' to the corresponding null node. We have to lock
> + * it before calling null_nodeget().
> + */
> + vn_lock(dvp, LK_SHARED | LK_RETRY);
> + error =3D null_nodeget(ap->a_vp->v_mount, dvp, ap->a_vpp);
> + if (error) {
> + vrele(dvp);
> + vdrop(dvp);
> + }
> + return (error);
> +}
> +
> /*
> * Global vfs data structures
> */
> @@ -743,4 +771,5 @@
> .vop_strategy =3D VOP_EOPNOTSUPP,
> .vop_unlock =3D null_unlock,
> .vop_vptofh =3D null_vptofh,
> + .vop_vptocnp =3D null_vptocnp,
> };
I do not think that nullfs-specific method is needed.
I already mailed the following patch to the reporters.
diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
index 5a6823f..38da43f 100644
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -742,5 +742,6 @@ struct vop_vector null_vnodeops =3D {
.vop_setattr =3D null_setattr,
.vop_strategy =3D VOP_EOPNOTSUPP,
.vop_unlock =3D null_unlock,
+ .vop_vptocnp =3D vop_stdvptocnp,
.vop_vptofh =3D null_vptofh,
};
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