New option "--direct-io".

src/main/help.c

@@ -93,6 +93,8 @@ void display_help(void)
 		 N_("stop after --size bytes have been transferred")},
 		{"-Y", "--sync", 0,
 		 N_("flush cache to disk after every write")},
+		{"-K", "--direct-io", 0,
+		 N_("use direct I/O to bypass cache")},
 #ifdef HAVE_IPC
 		{"-R", "--remote", N_("PID"),
 		 N_("update settings of process PID")},

src/main/main.c

@@ -202,6 +202,7 @@ int main(int argc, char **argv)
 	pv_state_skip_errors_set(state, opts->skip_errors);
 	pv_state_stop_at_size_set(state, opts->stop_at_size);
 	pv_state_sync_after_write_set(state, opts->sync_after_write);
+	pv_state_direct_io_set(state, opts->direct_io);
 	pv_state_rate_limit_set(state, opts->rate_limit);
 	pv_state_target_buffer_size_set(state, opts->buffer_size);
 	pv_state_no_splice_set(state, opts->no_splice);

src/main/options.c

@@ -83,6 +83,7 @@ opts_t opts_parse(int argc, char **argv)
 		{"skip-errors", 0, NULL, (int) 'E'},
 		{"stop-at-size", 0, NULL, (int) 'S'},
 		{"sync", 0, NULL, (int) 'Y'},
+		{"direct-io", 0, NULL, (int) 'K'},
 		{"remote", 1, NULL, (int) 'R'},
 		{"pidfile", 1, NULL, (int) 'P'},
 		{"watchfd", 1, NULL, (int) 'd'},
@@ -92,7 +93,7 @@ opts_t opts_parse(int argc, char **argv)
 	int option_index = 0;
 #endif
 	char *short_options =
-	    "hVpteIrab8TA:fnqcWD:s:l0i:w:H:N:F:L:B:CESYR:P:d:m:";
+	    "hVpteIrab8TA:fnqcWD:s:l0i:w:H:N:F:L:B:CESYKR:P:d:m:";
 	int c, numopts;
 	unsigned int check_pid;
 	int check_fd;
@@ -337,6 +338,9 @@ opts_t opts_parse(int argc, char **argv)
 		case 'Y':
 			opts->sync_after_write = true;
 			break;
+		case 'K':
+			opts->direct_io = true;
+			break;
 		case 'R':
 			opts->remote = pv_getnum_ui(optarg);
 			break;