+static int switch_ioscheduler(struct thread_data *td)
+{
+ char tmp[256], tmp2[128];
+ FILE *f;
+ int ret;
+
+ sprintf(tmp, "%s/queue/scheduler", td->sysfs_root);
+
+ f = fopen(tmp, "r+");
+ if (!f) {
+ td_verror(td, errno);
+ return 1;
+ }
+
+ /*
+ * Set io scheduler.
+ */
+ ret = fwrite(td->ioscheduler, strlen(td->ioscheduler), 1, f);
+ if (ferror(f) || ret != 1) {
+ td_verror(td, errno);
+ fclose(f);
+ return 1;
+ }
+
+ rewind(f);
+
+ /*
+ * Read back and check that the selected scheduler is now the default.
+ */
+ ret = fread(tmp, 1, sizeof(tmp), f);
+ if (ferror(f) || ret < 0) {
+ td_verror(td, errno);
+ fclose(f);
+ return 1;
+ }
+
+ sprintf(tmp2, "[%s]", td->ioscheduler);
+ if (!strstr(tmp, tmp2)) {
+ fprintf(stderr, "fio: io scheduler %s not found\n", td->ioscheduler);
+ td_verror(td, EINVAL);
+ fclose(f);
+ return 1;
+ }
+
+ fclose(f);
+ return 0;
+}
+