nfsd: CLOSE SHOULD return the invalid special stateid for NFSv4.x (x>0)

BugLink: http://bugs.launchpad.net/bugs/1755509

[ Upstream commit fb500a7c ]
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

fs/nfsd/nfs4state.c

@@ -63,6 +63,9 @@ static const stateid_t zero_stateid = {
 static const stateid_t currentstateid = {
 	.si_generation = 1,
 };
+static const stateid_t close_stateid = {
+	.si_generation = 0xffffffffU,
+};
 
 static u64 current_sessionid = 1;
 
@@ -5243,6 +5246,11 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	nfsd4_close_open_stateid(stp);
 	mutex_unlock(&stp->st_mutex);
 
+	/* See RFC5661 sectionm 18.2.4 */
+	if (stp->st_stid.sc_client->cl_minorversion)
+		memcpy(&close->cl_stateid, &close_stateid,
+				sizeof(close->cl_stateid));
+
 	/* put reference from nfs4_preprocess_seqid_op */
 	nfs4_put_stid(&stp->st_stid);
 out: