/*
 * mmap vs extent issue
 *
 * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/fs.h>
#include <linux/fiemap.h>

static void check_fiemap(int fd)
{
	struct fiemap *fiemap;
	unsigned long i, ex_size;

	fiemap = malloc(sizeof(struct fiemap));
	if (!fiemap) {
		perror("malloc");
		exit(1);
	}

	memset(fiemap, 0, sizeof(struct fiemap));
	fiemap->fm_length = ~0;

	if (ioctl(fd, FS_IOC_FIEMAP, fiemap) == -1) {
		perror("ioctl(FIEMAP)");
		exit(1);
	}

	ex_size = sizeof(struct fiemap_extent) * fiemap->fm_mapped_extents;

	fiemap = realloc(fiemap, sizeof(struct fiemap) + ex_size);
	if (!fiemap) {
		perror("realloc");
		exit(1);
	}

	memset(fiemap->fm_extents, 0, ex_size);
	fiemap->fm_extent_count = fiemap->fm_mapped_extents;
	fiemap->fm_mapped_extents = 0;

	if (ioctl(fd, FS_IOC_FIEMAP, fiemap) < 0) {
		perror("ioctl(FIEMAP)");
		exit(1);
	}

	for (i = 0; i < fiemap->fm_mapped_extents; i++) {
		unsigned long start = fiemap->fm_extents[i].fe_logical;
		unsigned long end = fiemap->fm_extents[i].fe_logical +
					fiemap->fm_extents[i].fe_length;

		if (start <= 48*1024 && end > 48*1024) {
			printf("GOOD\n");
			exit(0);
		}
	}

	printf("BAD:\n");
	for (i = 0; i < fiemap->fm_mapped_extents; i++) {
		printf("%ld:\t%016llx %016llx\n", i,
			fiemap->fm_extents[i].fe_logical,
			fiemap->fm_extents[i].fe_length);
	}

	exit(1);
}

int main(int argc, char *argv[])
{
	char name[] = "mmap-lseek-XXXXXX";
	int fd;
	char *p;

	fd = mkstemp(name);
	if (fd == -1) {
		perror("mkstemp");
		exit(1);
	}

	/* Create a 48 kB file */
	lseek(fd, 48 * 1024 - 1, SEEK_SET);
	if (write(fd, "\0", 1) != 1) {
		perror("write");
		exit(1);
	}

	/* Map it, allowing space for it to grow */
	p = mmap(NULL, 128 * 1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (p == MAP_FAILED) {
		perror("mmap");
		exit(1);
	}

	/* Write to the start of the file */
	*(p) = 1;

	/* Extend the file */
	lseek(fd, 128 * 1024 - 1, SEEK_SET);
	if (write(fd, "\0", 1) != 1) {
		perror("write");
		exit(1);
	}

	/* write to the new space in the first page */
	*(p + 49 * 1024) = 1;

	munmap(p, 128 * 1024);

	check_fiemap(fd);

	close(fd);

	return 0;
}