// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2023  Red Hat, Inc.
 *
 * Author: Gavin Shan <gshan@redhat.com>
 *
 * Attempt to reproduce the xfs issue that Zhenyu observed.
 * The idea is to mimic QEMU's behavior to have private
 * mmap'ed VMA on xfs file (/tmp/test_data). The program
 * should be put into cgroup where the memory limit is set,
 * so that memory claim is enforced.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/syscall.h>
#include <sys/mman.h>

#define TEST_FILENAME	"/tmp/test_data"
#define TEST_MEM_SIZE	0x40000000

static void hold(int argc, const char *desc)
{
	int opt;

	if (argc <= 1)
		return;

	fprintf(stdout, "%s\n", desc);
	scanf("%c", &opt);
}
	
int main(int argc, char **argv)
{
	int fd = 0;
	void *buf = (void *)-1, *p;
	int pgsize = getpagesize();
	int ret;

	fd = open(TEST_FILENAME, O_RDWR);
	if (fd < 0) {
		fprintf(stderr, "Unable to open <%s>\n", TEST_FILENAME);
		return -EIO;
	}

	hold(argc, "Press any key to mmap...\n");
	buf = mmap(NULL, TEST_MEM_SIZE, PROT_READ | PROT_WRITE,
		   MAP_PRIVATE, fd, 0);
	if (buf == (void *)-1) {
		fprintf(stderr, "Unable to mmap <%s>\n", TEST_FILENAME);
		goto cleanup;
	}

	fprintf(stdout, "mmap'ed at 0x%p\n", buf);
	ret = madvise(buf, TEST_MEM_SIZE, MADV_HUGEPAGE);
        if (ret) {
		fprintf(stderr, "Unable to madvise(MADV_HUGEPAGE)\n");
		goto cleanup;
	}

        hold(argc, "Press any key to populate...");
        fprintf(stdout, "Populate area at 0x%lx, size=0x%x\n",
                (unsigned long)buf, TEST_MEM_SIZE);
	ret = madvise(buf, TEST_MEM_SIZE, MADV_POPULATE_WRITE);
	if (ret) {
		fprintf(stderr, "Unable to madvise(MADV_POPULATE_WRITE)\n");
		goto cleanup;
	}
	
cleanup:
	hold(argc, "Press any key to munmap...");
	if (buf != (void *)-1)
		munmap(buf, TEST_MEM_SIZE);
	hold(argc, "Press any key to close...");
	if (fd > 0)
		close(fd);

	hold(argc, "Press any key to exit...");
	return 0;
}