Re: tstile syndrome

["Matt W. Benjamin" <matt%linuxbox.com@localhost>]

Hi,

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.

Regards,

Matt

----- "David Holland" <dholland-tech%NetBSD.org@localhost> 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
> VFS
> >> 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
> dholland%netbsd.org@localhost

-- 

Matt Benjamin

The Linux Box
206 South Fifth Ave. Suite 150
Ann Arbor, MI  48104

http://linuxbox.com

tel. 734-761-4689
fax. 734-769-8938
cel. 734-216-5309