Date: Thu, 22 Feb 2007 16:11:52 -0600 From: Eric Anderson <anderson@freebsd.org> To: Pawel Jakub Dawidek <pjd@freebsd.org> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: question about vfs_lookup Message-ID: <45DE1528.8020902@freebsd.org> In-Reply-To: <20070217210322.GB64936@garage.freebsd.pl> References: <45D69918.3000008@freebsd.org> <20070217210322.GB64936@garage.freebsd.pl>
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On 02/17/07 15:03, Pawel Jakub Dawidek wrote:
> 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 possibly ever get executed, since right before it there is a condition that would cause a panic.
>>
>> 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 '/'.
That makes a lot more sense now.. Thanks :)
Eric
>> In sys/kern/vfs_lookup.c:
>> 710 KASSERT((cnp->cn_flags & ISLASTCN) || *ndp->ni_next == '/',
>> 711 ("lookup: invalid path state."));
>> 712 if (*ndp->ni_next == '/') {
>> 713 cnp->cn_nameptr = ndp->ni_next;
>> 714 while (*cnp->cn_nameptr == '/') {
>> 715 cnp->cn_nameptr++;
>> 716 ndp->ni_pathlen--;
>> 717 }
>> 718 if (ndp->ni_dvp != dp)
>> 719 vput(ndp->ni_dvp);
>> 720 else
>> 721 vrele(ndp->ni_dvp);
>> 722 VFS_UNLOCK_GIANT(dvfslocked);
>> 723 dvfslocked = vfslocked; /* dp becomes dvp in dirloop */
>> 724 vfslocked = 0;
>> 725 goto dirloop;
>> 726 }
>
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