return NULL;
 }
 
+/*
+ * Return 1 iff clp's clientid establishment method matches the use_exchange_id
+ * parameter. Matching is based on the fact the at least one of the
+ * EXCHGID4_FLAG_USE_{NON_PNFS,PNFS_MDS,PNFS_DS} flags must be set for v4.1
+ *
+ * FIXME: we need to unify the clientid namespaces for nfsv4.x
+ * and correctly deal with client upgrade/downgrade in EXCHANGE_ID
+ * and SET_CLIENTID{,_CONFIRM}
+ */
+static inline int
+match_clientid_establishment(struct nfs4_client *clp, bool use_exchange_id)
+{
+       bool has_exchange_flags = (clp->cl_exchange_flags != 0);
+       return use_exchange_id == has_exchange_flags;
+}
+
 static struct nfs4_client *
-find_confirmed_client_by_str(const char *dname, unsigned int hashval)
+find_confirmed_client_by_str(const char *dname, unsigned int hashval,
+                            bool use_exchange_id)
 {
        struct nfs4_client *clp;
 
        list_for_each_entry(clp, &conf_str_hashtbl[hashval], cl_strhash) {
-               if (same_name(clp->cl_recdir, dname))
+               if (same_name(clp->cl_recdir, dname) &&
+                   match_clientid_establishment(clp, use_exchange_id))
                        return clp;
        }
        return NULL;
 }
 
 static struct nfs4_client *
-find_unconfirmed_client_by_str(const char *dname, unsigned int hashval)
+find_unconfirmed_client_by_str(const char *dname, unsigned int hashval,
+                              bool use_exchange_id)
 {
        struct nfs4_client *clp;
 
        list_for_each_entry(clp, &unconf_str_hashtbl[hashval], cl_strhash) {
-               if (same_name(clp->cl_recdir, dname))
+               if (same_name(clp->cl_recdir, dname) &&
+                   match_clientid_establishment(clp, use_exchange_id))
                        return clp;
        }
        return NULL;
        nfs4_lock_state();
        status = nfs_ok;
 
-       conf = find_confirmed_client_by_str(dname, strhashval);
+       conf = find_confirmed_client_by_str(dname, strhashval, true);
        if (conf) {
                if (!same_verf(&verf, &conf->cl_verifier)) {
                        /* 18.35.4 case 8 */
                }
        }
 
-       unconf  = find_unconfirmed_client_by_str(dname, strhashval);
+       unconf  = find_unconfirmed_client_by_str(dname, strhashval, true);
        if (unconf) {
                /*
                 * Possible retry or client restart.  Per 18.35.4 case 4,
        strhashval = clientstr_hashval(dname);
 
        nfs4_lock_state();
-       conf = find_confirmed_client_by_str(dname, strhashval);
+       conf = find_confirmed_client_by_str(dname, strhashval, false);
        if (conf) {
                /* RFC 3530 14.2.33 CASE 0: */
                status = nfserr_clid_inuse;
         * has a description of SETCLIENTID request processing consisting
         * of 5 bullet points, labeled as CASE0 - CASE4 below.
         */
-       unconf = find_unconfirmed_client_by_str(dname, strhashval);
+       unconf = find_unconfirmed_client_by_str(dname, strhashval, false);
        status = nfserr_resource;
        if (!conf) {
                /*
                        unsigned int hash =
                                clientstr_hashval(unconf->cl_recdir);
                        conf = find_confirmed_client_by_str(unconf->cl_recdir,
-                                                                       hash);
+                                                           hash, false);
                        if (conf) {
                                nfsd4_remove_clid_dir(conf);
                                expire_client(conf);
 }
 
 int
-nfs4_has_reclaimed_state(const char *name)
+nfs4_has_reclaimed_state(const char *name, bool use_exchange_id)
 {
        unsigned int strhashval = clientstr_hashval(name);
        struct nfs4_client *clp;
 
-       clp = find_confirmed_client_by_str(name, strhashval);
+       clp = find_confirmed_client_by_str(name, strhashval, use_exchange_id);
        return clp ? 1 : 0;
 }