Re: [PATCH v2 1/2] NFSD: added FREE_STATEID operation

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, May 16, 2011 at 03:43:40PM -0400, bjschuma@netapp.com wrote:
> +static __be32
> +nfsd4_free_file_stateid(stateid_t *stateid)
> +{
> +	struct nfs4_stateid *stp = search_for_stateid(stateid);
> +	if (!stp)
> +		return nfserr_bad_stateid;
> +	if (stateid->si_generation != 0) {
> +		if (stateid->si_generation < stp->st_stateid.si_generation)
> +			return nfserr_old_stateid;
> +		if (stateid->si_generation > stp->st_stateid.si_generation)
> +			return nfserr_bad_stateid;
> +	}
> +
> +	if (check_for_locks(stp->st_file, stp->st_stateowner))
> +		return nfserr_locks_held;

I think this catches a lock stateid, but not an open stateid that has
associated lock stateid's that in turn hold locks.

Hm, also:

	"The FREE_STATEID operation is used to free a stateid that no
	longer has any associated locks (including opens, byte-range
	locks, delegations, and layouts)"

So an open stateid also shouldn't be freeable as long as there are opens
associated with it.

Also I guess a client shouldn't be permitted to free a delegation that
it still holds.  That means we'll always just return nfserr_locks for
delegation stateid's.  I assume free_stateid is only useful in this case
for the case where a server forcibly revokes part of the client's state
and leaves some "stub" stateid's around in place of the revoked ones.

--b.