Date: Sat, 17 Feb 2007 22:03:22 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Eric Anderson <anderson@freebsd.org> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: question about vfs_lookup Message-ID: <20070217210322.GB64936@garage.freebsd.pl> In-Reply-To: <45D69918.3000008@freebsd.org> References: <45D69918.3000008@freebsd.org>
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On Fri, Feb 16, 2007 at 11:56:40PM -0600, Eric Anderson wrote:
> I'm just curious about how this block (starting at line 712) could possib=
ly ever get executed, since right before it there is a condition that would=
cause a panic.
>=20
> Can anyone explain this please?
You read KASSERT(9) in a wrong way. The condition used in assertion says
"don't panic if the condition is true". Here we panic when flag ISLASTCN
is not set and *ndp->ni_next is not equal to '/'.
> In sys/kern/vfs_lookup.c:
> 710 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next =3D=3D '/=
',
> 711 ("lookup: invalid path state."));
> 712 if (*ndp->ni_next =3D=3D '/') {
> 713 cnp->cn_nameptr =3D ndp->ni_next;
> 714 while (*cnp->cn_nameptr =3D=3D '/') {
> 715 cnp->cn_nameptr++;
> 716 ndp->ni_pathlen--;
> 717 }
> 718 if (ndp->ni_dvp !=3D dp)
> 719 vput(ndp->ni_dvp);
> 720 else
> 721 vrele(ndp->ni_dvp);
> 722 VFS_UNLOCK_GIANT(dvfslocked);
> 723 dvfslocked =3D vfslocked; /* dp becomes dvp in dirloo=
p */
> 724 vfslocked =3D 0;
> 725 goto dirloop;
> 726 }
--=20
Pawel Jakub Dawidek http://www.wheel.pl
pjd@FreeBSD.org http://www.FreeBSD.org
FreeBSD committer Am I Evil? Yes, I Am!
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