helpers: add io_uring_create_file() helper

cleanup: add io_uring_create_file() helper,
and replace create_file() with io_uring_calloc() in tests.

Signed-off-by: Zhiqiang Liu <[email protected]>
diff --git a/test/helpers.c b/test/helpers.c
index af6d936..c5a82fa 100644
--- a/test/helpers.c
+++ b/test/helpers.c
@@ -4,6 +4,10 @@
  */
 #include <stdlib.h>
 #include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
 
 #include "helpers.h"
 
@@ -41,4 +45,25 @@
 	return ret;
 }
 
+/*
+ * Helper for creating file and write @size byte buf with 0xaa value in the file.
+ */
+void io_uring_create_file(const char *file, size_t size)
+{
+	ssize_t ret;
+	char *buf;
+	int fd; 
+
+	buf = io_uring_malloc(size);
+	memset(buf, 0xaa, size);
+
+	fd = open(file, O_WRONLY | O_CREAT, 0644);
+	assert(fd >= 0);
+
+	ret = write(fd, buf, size);
+	fsync(fd);
+	close(fd);
+	free(buf);
+	assert(ret == size);
+}