nfsd: Ensure that the laundromat unhashes the client before releasing locks

If we leave the client on the confirmed/unconfirmed tables, and leave
the sessions visible on the sessionid_hashtbl, then someone might
find them before we've had a chance to destroy them.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -4125,13 +4125,15 @@ nfs4_laundromat(struct nfsd_net *nn)
 				clp->cl_clientid.cl_id);
 			continue;
 		}
-		list_move(&clp->cl_lru, &reaplist);
+		unhash_client_locked(clp);
+		list_add(&clp->cl_lru, &reaplist);
 	}
 	spin_unlock(&nn->client_lock);
 	list_for_each_safe(pos, next, &reaplist) {
 		clp = list_entry(pos, struct nfs4_client, cl_lru);
 		dprintk("NFSD: purging unused client (clientid %08x)\n",
 			clp->cl_clientid.cl_id);
+		list_del_init(&clp->cl_lru);
 		expire_client(clp);
 	}
 	spin_lock(&state_lock);