use 'const' where it is required

protect variables and parameters from programmer's point of view with
'constness'

Signed-off-by: Denis Pronin <dannftk@yandex.ru>

client.c

@@ -34,7 +34,7 @@ static void handle_start(struct fio_client *client, struct fio_net_cmd *cmd);
 static void convert_text(struct fio_net_cmd *cmd);
 static void client_display_thread_status(struct jobs_eta *je);
 
-struct client_ops fio_client_ops = {
+struct client_ops const fio_client_ops = {
  .text = handle_text,
  .disk_util = handle_du,
  .thread_status = handle_ts,
@@ -446,7 +446,7 @@ int fio_client_add_ini_file(void *cookie, const char *ini_file, bool remote)
  return 0;
 }
 
-int fio_client_add(struct client_ops *ops, const char *hostname, void **cookie)
+int fio_client_add(struct client_ops const *ops, const char *hostname, void **cookie)
 {
  struct fio_client *existing = *cookie;
  struct fio_client *client;
@@ -1772,7 +1772,7 @@ static int fio_send_file(struct fio_client *client, struct cmd_sendfile *pdu,
 
 int fio_handle_client(struct fio_client *client)
 {
- struct client_ops *ops = client->ops;
+ struct client_ops const *ops = client->ops;
  struct fio_net_cmd *cmd;
 
  dprint(FD_NET, "client: handle %s\n", client->hostname);
@@ -1957,7 +1957,7 @@ int fio_clients_send_trigger(const char *cmd)
  return 0;
 }
 
-static void request_client_etas(struct client_ops *ops)
+static void request_client_etas(struct client_ops const *ops)
 {
  struct fio_client *client;
  struct flist_head *entry;
@@ -2089,7 +2089,7 @@ static int fio_check_clients_timed_out(void)
  return ret;
 }
 
-int fio_handle_clients(struct client_ops *ops)
+int fio_handle_clients(struct client_ops const *ops)
 {
  struct pollfd *pfds;
  int i, ret = 0, retval = 0;

client.h

@@ -69,7 +69,7 @@ struct fio_client {
  uint16_t argc;
  char **argv;
 
- struct client_ops *ops;
+ struct client_ops const *ops;
  void *client_data;
 
  struct client_file *files;
@@ -84,7 +84,7 @@ typedef void (client_eta_op)(struct jobs_eta *je);
 typedef void (client_timed_out_op)(struct fio_client *);
 typedef void (client_jobs_eta_op)(struct fio_client *client, struct jobs_eta *je);
 
-extern struct client_ops fio_client_ops;
+extern struct client_ops const fio_client_ops;
 
 struct client_ops {
  client_cmd_op *text;
@@ -128,8 +128,8 @@ extern int fio_start_client(struct fio_client *);
 extern int fio_start_all_clients(void);
 extern int fio_clients_send_ini(const char *);
 extern int fio_client_send_ini(struct fio_client *, const char *, bool);
-extern int fio_handle_clients(struct client_ops *);
-extern int fio_client_add(struct client_ops *, const char *, void **);
+extern int fio_handle_clients(struct client_ops const*);
+extern int fio_client_add(struct client_ops const*, const char *, void **);
 extern struct fio_client *fio_client_add_explicit(struct client_ops *, const char *, int, int);
 extern void fio_client_add_cmd_option(void *, const char *);
 extern int fio_client_add_ini_file(void *, const char *, bool);