NFSv4: Replace closed stateids with the "invalid special stateid"

When decoding a CLOSE, replace the stateid returned by the server
with the "invalid special stateid" described in RFC5661, Section 8.2.3.

In nfs_set_open_stateid_locked, ignore stateids from closed state.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4_fs.h

@@ -481,6 +481,7 @@ extern int nfs4_sequence_done(struct rpc_task *task,
 extern void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp);
 
 extern const nfs4_stateid zero_stateid;
+extern const nfs4_stateid invalid_stateid;
 
 /* nfs4super.c */
 struct nfs_mount_info;

fs/nfs/nfs4state.c

@@ -69,6 +69,14 @@ const nfs4_stateid zero_stateid = {
 	{ .data = { 0 } },
 	.type = NFS4_SPECIAL_STATEID_TYPE,
 };
+const nfs4_stateid invalid_stateid = {
+	{
+		.seqid = cpu_to_be32(0xffffffffU),
+		.other = { 0 },
+	},
+	.type = NFS4_INVALID_STATEID_TYPE,
+};
+
 static DEFINE_MUTEX(nfs_clid_init_mutex);
 
 int nfs4_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)

fs/nfs/nfs4xdr.c

@@ -4385,6 +4385,14 @@ static int decode_delegation_stateid(struct xdr_stream *xdr, nfs4_stateid *state
 	return decode_stateid(xdr, stateid);
 }
 
+static int decode_invalid_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
+{
+	nfs4_stateid dummy;
+
+	nfs4_stateid_copy(stateid, &invalid_stateid);
+	return decode_stateid(xdr, &dummy);
+}
+
 static int decode_close(struct xdr_stream *xdr, struct nfs_closeres *res)
 {
 	int status;
@@ -4393,7 +4401,7 @@ static int decode_close(struct xdr_stream *xdr, struct nfs_closeres *res)
 	if (status != -EIO)
 		nfs_increment_open_seqid(status, res->seqid);
 	if (!status)
-		status = decode_open_stateid(xdr, &res->stateid);
+		status = decode_invalid_stateid(xdr, &res->stateid);
 	return status;
 }
 
@@ -6108,6 +6116,8 @@ static int decode_layoutreturn(struct xdr_stream *xdr,
 	res->lrs_present = be32_to_cpup(p);
 	if (res->lrs_present)
 		status = decode_layout_stateid(xdr, &res->stateid);
+	else
+		nfs4_stateid_copy(&res->stateid, &invalid_stateid);
 	return status;
 out_overflow:
 	print_overflow_msg(__func__, xdr);