question about vfs_lookup

[Pawel Jakub Dawidek]

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 '/'.

> 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         }

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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