NFSD: Modernize nfsd4_release_lockowner()

Refactor: Use existing helpers that other lock operations use. This
change removes several automatic variables, so re-organize the
variable declarations for readability.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -7530,16 +7530,13 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
 			union nfsd4_op_u *u)
 {
 	struct nfsd4_release_lockowner *rlockowner = &u->release_lockowner;
+	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	clientid_t *clid = &rlockowner->rl_clientid;
-	struct nfs4_stateowner *sop;
-	struct nfs4_lockowner *lo = NULL;
 	struct nfs4_ol_stateid *stp;
-	struct xdr_netobj *owner = &rlockowner->rl_owner;
-	unsigned int hashval = ownerstr_hashval(owner);
-	__be32 status;
-	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	struct nfs4_lockowner *lo;
 	struct nfs4_client *clp;
-	LIST_HEAD (reaplist);
+	LIST_HEAD(reaplist);
+	__be32 status;
 
 	dprintk("nfsd4_release_lockowner clientid: (%08x/%08x):\n",
 		clid->cl_boot, clid->cl_id);
@@ -7547,30 +7544,19 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
 	status = set_client(clid, cstate, nn);
 	if (status)
 		return status;
-
 	clp = cstate->clp;
-	/* Find the matching lock stateowner */
-	spin_lock(&clp->cl_lock);
-	list_for_each_entry(sop, &clp->cl_ownerstr_hashtbl[hashval],
-			    so_strhash) {
 
-		if (sop->so_is_open_owner || !same_owner_str(sop, owner))
-			continue;
-
-		if (atomic_read(&sop->so_count) != 1) {
-			spin_unlock(&clp->cl_lock);
-			return nfserr_locks_held;
-		}
-
-		lo = lockowner(sop);
-		nfs4_get_stateowner(sop);
-		break;
-	}
+	spin_lock(&clp->cl_lock);
+	lo = find_lockowner_str_locked(clp, &rlockowner->rl_owner);
 	if (!lo) {
 		spin_unlock(&clp->cl_lock);
 		return status;
 	}
-
+	if (atomic_read(&lo->lo_owner.so_count) != 2) {
+		spin_unlock(&clp->cl_lock);
+		nfs4_put_stateowner(&lo->lo_owner);
+		return nfserr_locks_held;
+	}
 	unhash_lockowner_locked(lo);
 	while (!list_empty(&lo->lo_owner.so_stateids)) {
 		stp = list_first_entry(&lo->lo_owner.so_stateids,