Re: vwakeup: neg numoutput

[Andrew Doran <ad%netbsd.org@localhost>]

On Tue, Jul 01, 2008 at 02:10:39PM +0200, Manuel Bouyer wrote:

> vfs_subr2.c has another place which makes me believe we can't use atomic ops
> alone to incement v_numoutput:
> 315: KASSERT(vp->v_numoutput == 0 && LIST_EMPTY(&vp->v_dirtyblkhd)); 
> if we can increment v_numoutput without hodling the lock, this KASSERT may
> fire because v_numoutput may be non-zero here after the VOP_FSYNC().

That assertion's broken because the vnode pager can start writes even if
another thread holds the vnode locked.

Andrew