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Re: tstile syndrome


For what it may be worth, as someone working on an out-of-tree filesystem which 
will have to survive a netbsd vnode locking transition should this change 
occur, I don't feel particularly eager to see vnode locking changing out from 
under me.  I wish I understood more clearly what change is actually being 
proposed.  The vnode locking paradigm as such seems far from broken, it is a 
known quantity, and for many years has been relatively consistent across the 
BSD family of kernels, or so it seems to me.



----- "David Holland" <> wrote:

> On Fri, Sep 11, 2009 at 03:14:09PM -0700, Jason Thorpe wrote:
> >> Such as? Please give clear examples. Moving the locks to below the
> >> layer does not change any of the ordering constraints or any of
> the
> >> hard problems (vnode recycle, rename, etc.) but only forces
> cutting
> >> and pasting 30 copies of what was previously FS-independent code
> into
> >> every FS.
> There are only two things seriously wrong with the vnode locking we
> currently have; one is that many VOP calls are not symmetric (that
> is,
> locks are in a different state upon return) and the other is that
> namei is an octopus. The first of these problems is readily fixed,
> although because the mess has been cut and pasted 30 times it's not
> so
> trivial to get done safely. The second I'm working on.
> -- 
> David A. Holland


Matt Benjamin

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