Date: Tue, 07 Dec 2004 12:36:15 +0100 From: Thomas Nystrom <thn@saeab.se> To: Alexander Kabaev <kan@FreeBSD.org> Cc: freebsd-fs@FreeBSD.org Subject: Re: Dead vnode locking against itself Message-ID: <41B595AF.7050602@saeab.se> In-Reply-To: <20041206231347.GA18156@freefall.freebsd.org> References: <41B0C899.C005AE1E@saeab.se> <20041206205628.GA3309@freefall.freebsd.org> <41B4D832.2D886E86@saeab.se> <20041206231347.GA18156@freefall.freebsd.org>
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Alexander Kabaev wrote:
>=20
> Unless I am reading sources wrong, the scenario you describe should not=
> happen. vgonel resets the vnode type to VBAD just before releasing vnod=
e
> locks for the last time and vtryrecycle avoids calling vgonel on vnodes=
> with that type:
>=20
> if (vp->v_type !=3D VBAD) {
> VOP_UNLOCK(vp, 0, td); =20
> vgonel(vp, td);
> VI_LOCK(vp);
> } else
> VOP_UNLOCK(vp, 0, td);
>=20
> The vnode data below shows that vnode has a type of VDIR and evidently =
its
> v_op is set to dead_vnodeops. At the same time, v_tag is "none", which
> suggests that vnode has been processed by vclean already, but vgonel ha=
d
> not yet have a chance to update vnode's type. Just out of curiosity, ca=
n you
> try your code with VI_UNLOCK(vp);/VI_LOCK(vp); pair removed from the
> vgonel function around line 294? This is the only place where vnode int=
erlock
> is released after vclean completes and before vgonel sets the vnode typ=
e.
> There is no point in unlocking the interlock just to lock it again
> immediately anyway.
Ok, I missed that VBAD setting. Then I assume that it is arla that is=20
playing around with nodes after it has released via vgonel(). I have=20
seen other indications of that.....
/thn
--=20
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