+ struct nfs4_client *unconf, *conf, *new;
+ int status;
+ unsigned int strhashval;
+ char dname[HEXDIR_LEN];
+ nfs4_verifier verf = exid->verifier;
+ u32 ip_addr = svc_addr_in(rqstp)->sin_addr.s_addr;
+
+ dprintk("%s rqstp=%p exid=%p clname.len=%u clname.data=%p "
+ " ip_addr=%u flags %x, spa_how %d\n",
+ __func__, rqstp, exid, exid->clname.len, exid->clname.data,
+ ip_addr, exid->flags, exid->spa_how);
+
+ if (!check_name(exid->clname) || (exid->flags & ~EXCHGID4_FLAG_MASK_A))
+ return nfserr_inval;
+
+ /* Currently only support SP4_NONE */
+ switch (exid->spa_how) {
+ case SP4_NONE:
+ break;
+ case SP4_SSV:
+ return nfserr_encr_alg_unsupp;
+ default:
+ BUG(); /* checked by xdr code */
+ case SP4_MACH_CRED:
+ return nfserr_serverfault; /* no excuse :-/ */
+ }
+
+ status = nfs4_make_rec_clidname(dname, &exid->clname);
+
+ if (status)
+ goto error;
+
+ strhashval = clientstr_hashval(dname);
+
+ nfs4_lock_state();
+ status = nfs_ok;
+
+ conf = find_confirmed_client_by_str(dname, strhashval);
+ if (conf) {
+ if (!same_verf(&verf, &conf->cl_verifier)) {
+ /* 18.35.4 case 8 */
+ if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
+ status = nfserr_not_same;
+ goto out;
+ }
+ /* Client reboot: destroy old state */
+ expire_client(conf);
+ goto out_new;
+ }
+ if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
+ /* 18.35.4 case 9 */
+ if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
+ status = nfserr_perm;
+ goto out;
+ }
+ expire_client(conf);
+ goto out_new;
+ }
+ if (ip_addr != conf->cl_addr &&
+ !(exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A)) {
+ /* Client collision. 18.35.4 case 3 */
+ status = nfserr_clid_inuse;
+ goto out;
+ }
+ /*
+ * Set bit when the owner id and verifier map to an already
+ * confirmed client id (18.35.3).
+ */
+ exid->flags |= EXCHGID4_FLAG_CONFIRMED_R;
+
+ /*
+ * Falling into 18.35.4 case 2, possible router replay.
+ * Leave confirmed record intact and return same result.
+ */
+ copy_verf(conf, &verf);
+ new = conf;
+ goto out_copy;
+ } else {
+ /* 18.35.4 case 7 */
+ if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
+ status = nfserr_noent;
+ goto out;
+ }
+ }
+
+ unconf = find_unconfirmed_client_by_str(dname, strhashval);
+ if (unconf) {
+ /*
+ * Possible retry or client restart. Per 18.35.4 case 4,
+ * a new unconfirmed record should be generated regardless
+ * of whether any properties have changed.
+ */
+ expire_client(unconf);
+ }
+
+out_new:
+ /* Normal case */
+ new = create_client(exid->clname, dname);
+ if (new == NULL) {
+ status = nfserr_resource;
+ goto out;
+ }
+
+ copy_verf(new, &verf);
+ copy_cred(&new->cl_cred, &rqstp->rq_cred);
+ new->cl_addr = ip_addr;
+ gen_clid(new);
+ gen_confirm(new);
+ add_to_unconfirmed(new, strhashval);
+out_copy:
+ exid->clientid.cl_boot = new->cl_clientid.cl_boot;
+ exid->clientid.cl_id = new->cl_clientid.cl_id;
+
+ new->cl_seqid = exid->seqid = 1;
+ nfsd4_set_ex_flags(new, exid);
+
+ dprintk("nfsd4_exchange_id seqid %d flags %x\n",
+ new->cl_seqid, new->cl_exchange_flags);
+ status = nfs_ok;
+
+out:
+ nfs4_unlock_state();
+error:
+ dprintk("nfsd4_exchange_id returns %d\n", ntohl(status));
+ return status;