ceph/qa/workunits/direct_io_test.c

/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2011 New Dream Network
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software
 * Foundation.  See file COPYING.
 *
 */
#define _GNU_SOURCE // for O_DIRECT

#include <errno.h>
#include <inttypes.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

/*
 * direct_io_test
 *
 * This test does some I/O using O_DIRECT.
 *
 * Semantics of O_DIRECT can be found at http://lwn.net/Articles/348739/
 *
 */

static int g_num_pages = 100;

static int g_duration = 10;

struct chunk {
	uint64_t offset;
	uint64_t pad0;
	uint64_t pad1;
	uint64_t pad2;
	uint64_t pad3;
	uint64_t pad4;
	uint64_t pad5;
	uint64_t not_offset;
} __attribute__((packed));

static int page_size;

static char temp_file[] = "direct_io_temp_file_XXXXXX";

static int safe_write(int fd, const void *buf, signed int len)
{
	const char *b = (const char*)buf;
	/* Handle EINTR and short writes */
	while (1) {
		int res = write(fd, b, len);
		if (res < 0) {
			int err = errno;
			if (err != EINTR) {
				return err;
			}
		}
		len -= res;
		b += res;
		if (len <= 0)
			return 0;
	}
}

static int do_read(int fd, char *buf, int buf_sz)
{
	/* We assume no short reads or EINTR. It's not really clear how
	 * those things interact with O_DIRECT. */
	int ret = read(fd, buf, buf_sz);
	if (ret < 0) {
		int err = errno;
		printf("do_read: error: %d (%s)\n", err, strerror(err));
		return err;
	}
	if (ret != buf_sz) {
		printf("do_read: short read\n");
		return -EIO;
	}
	return 0;
}

static int setup_temp_file(void)
{
	int fd;
	int64_t num_chunks, i;

	if (page_size % sizeof(struct chunk)) {
		printf("setup_big_file: page_size doesn't divide evenly "
			"into data blocks.\n");
		return -EINVAL;
	}

	fd = mkstemp(temp_file);
	if (fd < 0) {
		int err = errno;
		printf("setup_big_file: mkostemps failed with error %d\n", err);
		return err;
	}

	num_chunks = g_num_pages * (page_size / sizeof(struct chunk));
	for (i = 0; i < num_chunks; ++i) {
		int ret;
		struct chunk c;
		memset(&c, 0, sizeof(c));
		c.offset = i * sizeof(struct chunk);
		c.pad0 = 0;
		c.pad1 = 1;
		c.pad2 = 2;
		c.pad3 = 3;
		c.pad4 = 4;
		c.pad5 = 5;
		c.not_offset = ~c.offset;
		ret = safe_write(fd, &c, sizeof(struct chunk));
		if (ret) {
			printf("setup_big_file: safe_write failed with "
			       "error: %d\n", ret);
			TEMP_FAILURE_RETRY(close(fd));
			unlink(temp_file);
			return ret;
		}
	}
	TEMP_FAILURE_RETRY(close(fd));
	return 0;
}

static int verify_chunk(const struct chunk *c, uint64_t offset)
{
	if (c->offset != offset) {
		printf("verify_chunk(%" PRId64 "): bad offset value (got: %"
		       PRId64 ", expected: %" PRId64 "\n", offset, c->offset, offset);
		return EIO;
	}
	if (c->pad0 != 0) {
		printf("verify_chunk(%" PRId64 "): bad pad0 value\n", offset);
		return EIO;
	}
	if (c->pad1 != 1) {
		printf("verify_chunk(%" PRId64 "): bad pad1 value\n", offset);
		return EIO;
	}
	if (c->pad2 != 2) {
		printf("verify_chunk(%" PRId64 "): bad pad2 value\n", offset);
		return EIO;
	}
	if (c->pad3 != 3) {
		printf("verify_chunk(%" PRId64 "): bad pad3 value\n", offset);
		return EIO;
	}
	if (c->pad4 != 4) {
		printf("verify_chunk(%" PRId64 "): bad pad4 value\n", offset);
		return EIO;
	}
	if (c->pad5 != 5) {
		printf("verify_chunk(%" PRId64 "): bad pad5 value\n", offset);
		return EIO;
	}
	if (c->not_offset != ~offset) {
		printf("verify_chunk(%" PRId64 "): bad not_offset value\n",
		       offset);
		return EIO;
	}
	return 0;
}

static int do_o_direct_reads(void)
{
	int fd, ret;
	unsigned int i;
	void *buf = 0;
	time_t cur_time, end_time;
	ret = posix_memalign(&buf, page_size, page_size);
	if (ret) {
		printf("do_o_direct_reads: posix_memalign returned %d\n", ret);
		goto done;
	}

	fd = open(temp_file, O_RDONLY | O_DIRECT);
	if (fd < 0) {
		ret = errno;
		printf("do_o_direct_reads: error opening fd: %d\n", ret);
		goto free_buf;
	}

	// read the first chunk and see if it looks OK
	ret = do_read(fd, buf, page_size);
	if (ret)
		goto close_fd;
	ret = verify_chunk((struct chunk*)buf, 0);
	if (ret)
		goto close_fd;

	// read some random chunks and see how they look
	cur_time = time(NULL);
	end_time = cur_time + g_duration;
	i = 0;
	do {
		time_t next_time;
		uint64_t offset;
		int page;
		unsigned int seed;

		seed = i++;
		page = rand_r(&seed) % g_num_pages;
		offset = page;
		offset *= page_size;
		if (lseek64(fd, offset, SEEK_SET) == -1) {
			int err = errno;
			printf("lseek64(%" PRId64 ") failed: error %d (%s)\n",
			       offset, err, strerror(err));
			goto close_fd;
		}
		ret = do_read(fd, buf, page_size);
		if (ret)
			goto close_fd;
		ret = verify_chunk((struct chunk*)buf, offset);
		if (ret)
			goto close_fd;
		next_time = time(NULL);
		if (next_time > cur_time) {
			printf(".");
		}
		cur_time = next_time;
	} while (time(NULL) < end_time);

	printf("\ndo_o_direct_reads: SUCCESS\n");
close_fd:
	TEMP_FAILURE_RETRY(close(fd));
free_buf:
	free(buf);
done:
	return ret;
}

static void usage(char *argv0)
{
	printf("%s: tests direct I/O\n", argv0);
	printf("-d <seconds>:          sets duration to <seconds>\n");
	printf("-h:                    this help\n");
	printf("-p <pages>:            sets number of pages to allocate\n");
}

static void parse_args(int argc, char *argv[])
{
	int c;
	while ((c = getopt (argc, argv, "d:hp:")) != -1) {
		switch (c) {
		case 'd':
			g_duration = atoi(optarg);
			if (g_duration <= 0) {
				printf("tried to set invalid value of "
				       "g_duration: %d\n", g_num_pages);
				exit(1);
			}
			break;
		case 'h':
			usage(argv[0]);
			exit(0);
			break;
		case 'p':
			g_num_pages = atoi(optarg);
			if (g_num_pages <= 0) {
				printf("tried to set invalid value of "
				       "g_num_pages: %d\n", g_num_pages);
				exit(1);
			}
			break;
		case '?':
			usage(argv[0]);
			exit(1);
			break;
		default:
			usage(argv[0]);
			exit(1);
			break;
		}
	}
}

int main(int argc, char *argv[])
{
	int ret;

	parse_args(argc, argv);

	setvbuf(stdout, NULL, _IONBF, 0);

	page_size = getpagesize();

	ret = setup_temp_file();
	if (ret) {
		printf("setup_temp_file failed with error %d\n", ret);
		goto done;
	}

	ret = do_o_direct_reads();
	if (ret) {
		printf("do_o_direct_reads failed with error %d\n", ret);
		goto unlink_temp_file;
	}

unlink_temp_file:
	unlink(temp_file);
done:
	return ret;
}