Use sync-io with raw devices (significantly improves speed)

default.c

@@ -82,7 +82,7 @@ int fastwriter_default_open(fastwriter_t *fw, const char *name, fastwriter_flags
 	ctx->pa_block = 0;
 	ctx->prior_size = (size_t)-1;
 #ifdef SYNC_MODE
-	ctx->sync_mode = 0;
+//	ctx->sync_mode = 0;
 #endif /* SYNC_MODE */
 	open_flags &= ~(O_CREAT|O_NOATIME|O_LARGEFILE);
     } else if (!strcmp(fs, "ext4")) {