integrating nfsv4 locking with nlm and local locking

[Rick Macklem]

On Mon, 13 Apr 2009, John Baldwin wrote:

>
> You have to hold the vnode lock to set a VV flag always.  Even if you do an
> atomic operation to set your flag, another thread might be setting a flag at
> the same time using non-atomic ops and could clobber your change (if it does
> a read-modify-write and reads a value that pre-dates your atomic_set_int()
> but its write posts after your write).
>
Righto, thanks. (I should have realized that.) I guess I'll have to use a
VI_xxx flag or add a field to the vnode to make the scheme work. I am
just trying to come up with a stopgap solution until something more
comprehensive can be done w.r.t. handling delegations.

VI_xxx are currently used for handling the vnode and it doesn't seem
appropriate to add one of these to indicate "don't issue delegations".

How do others feel w.r.t. adding a VI_xxx flag vs adding v_disabledelegate
to the structure?

There is always the fallback position of shipping an nfsv4 server with
delegations disabled, until handling them when local VOPs are done, gets
resolved.

rick