nfsd: add locking to stateowner release

Once we remove the client_mutex, we'll need to properly protect
the stateowner reference counts using the cl_lock.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -937,9 +937,14 @@ release_all_access(struct nfs4_ol_stateid *stp)
 
 static void nfs4_put_stateowner(struct nfs4_stateowner *sop)
 {
-	if (!atomic_dec_and_test(&sop->so_count))
+	struct nfs4_client *clp = sop->so_client;
+
+	might_lock(&clp->cl_lock);
+
+	if (!atomic_dec_and_lock(&sop->so_count, &clp->cl_lock))
 		return;
 	sop->so_ops->so_unhash(sop);
+	spin_unlock(&clp->cl_lock);
 	kfree(sop->so_owner.data);
 	sop->so_ops->so_free(sop);
 }
@@ -3078,11 +3083,7 @@ static void hash_openowner(struct nfs4_openowner *oo, struct nfs4_client *clp, u
 
 static void nfs4_unhash_openowner(struct nfs4_stateowner *so)
 {
-	struct nfs4_client *clp = so->so_client;
-
-	spin_lock(&clp->cl_lock);
 	unhash_openowner_locked(openowner(so));
-	spin_unlock(&clp->cl_lock);
 }
 
 static void nfs4_free_openowner(struct nfs4_stateowner *so)
@@ -4842,11 +4843,7 @@ find_lockowner_str(clientid_t *clid, struct xdr_netobj *owner,
 
 static void nfs4_unhash_lockowner(struct nfs4_stateowner *sop)
 {
-	struct nfs4_client *clp = sop->so_client;
-
-	spin_lock(&clp->cl_lock);
 	unhash_lockowner_locked(lockowner(sop));
-	spin_unlock(&clp->cl_lock);
 }
 
 static void nfs4_free_lockowner(struct nfs4_stateowner *sop)