Re: NFS lockup after UDP fragments getting lost (was: 8.1 tstile lockup after nfs send error 51)

[maya%NetBSD.org@localhost]

On Wed, Jul 31, 2019 at 07:11:54AM -0700, Jason Thorpe wrote:
> 
> > On Jul 31, 2019, at 1:45 AM, Edgar Fuß <ef%math.uni-bonn.de@localhost> wrote:
> > 
> > NetBSD design error (or so Taylor says) that a vnode lock may be held accross I/O
> 
> 100%
> 
> NetBSD's VFS locking protocol needs a serious overhaul.  At least one other BSD-family VFS (the one in XNU) completely eliminated locking of vnodes at the VFS layer (it's all pushed into the file system back-ends who now have more control over their own locking requirements).  It does have some additional complexities around reference / busy counting and vnode identity, but it works very well in practice.
> 
> I don't know what FreeBSD has done in this area.
> 
> -- thorpej
> 

IMNT_MPSAFE, which NFS isn't?