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path: root/make-bcache.c
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#define _FILE_OFFSET_BITS	64
#define __USE_FILE_OFFSET64
#define _XOPEN_SOURCE 600

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <linux/fs.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <uuid/uuid.h>

#include "bcache.h"

uint64_t getblocks(int fd)
{
	uint64_t ret;
	struct stat statbuf;
	if (fstat(fd, &statbuf)) {
		perror("stat error\n");
		exit(EXIT_FAILURE);
	}
	ret = statbuf.st_size / 512;
	if (S_ISBLK(statbuf.st_mode))
		if (ioctl(fd, BLKGETSIZE, &ret)) {
			perror("ioctl error");
			exit(EXIT_FAILURE);
		}
	return ret;
}

uint64_t hatoi(const char *s)
{
	char *e;
	long long i = strtoll(s, &e, 10);
	switch (*e) {
		case 't':
		case 'T':
			i *= 1024;
		case 'g':
		case 'G':
			i *= 1024;
		case 'm':
		case 'M':
			i *= 1024;
		case 'k':
		case 'K':
			i *= 1024;
	}
	return i;
}

char *skip_spaces(const char *str)
{
	while (isspace(*str))
		++str;
	return (char *)str;
}

char *strim(char *s)
{
	size_t size;
	char *end;

	s = skip_spaces(s);
	size = strlen(s);
	if (!size)
		return s;

	end = s + size - 1;
	while (end >= s && isspace(*end))
		end--;
	*(end + 1) = '\0';

	return s;
}

ssize_t read_string_list(const char *buf, const char * const list[])
{
	size_t i;
	char *s, *d = strdup(buf);
	if (!d)
		return -ENOMEM;

	s = strim(d);

	for (i = 0; list[i]; i++)
		if (!strcmp(list[i], s))
			break;

	free(d);

	if (!list[i])
		return -EINVAL;

	return i;
}

void usage()
{
	printf("Usage: make-bcache [options] device\n"
	       "	-C, --cache		Format a cache device\n"
	       "	-B, --bdev		Format a backing device\n"
	       "	-b, --bucket		bucket size\n"
	       "	-w, --block		block size (hard sector size of SSD, often 2k)\n"
	       "	-U			UUID\n"
	       "	    --writeback		enable writeback\n"
	       "	    --discard		enable discards\n"
	       "	    --cache_replacement_policy=(lru|fifo)\n"
	       "	-h, --help		display this help and exit\n");
	exit(EXIT_FAILURE);
}

const char * const cache_replacement_policies[] = {
	"lru",
	"fifo",
	"random",
	NULL
};

int writeback;
int discard;
unsigned cache_replacement_policy;
uint64_t data_offset = 16;

struct option opts[] = {
	{ "cache",		0, NULL,	'C' },
	{ "bdev",		0, NULL,	'B' },
	{ "bucket",		1, NULL,	'b' },
	{ "block",		1, NULL,	'w' },
	{ "writeback",		0, &writeback,	1 },
	{ "discard",		0, &discard,	1 },
	{ "cache_replacement_policy", 1, NULL, 'p' },
//	{ "data_offset",	1, NULL,	'o' },
	{ "help",		0, NULL,	'h' },
	{ NULL,			0, NULL,	0 },
};

void write_sb(char *dev, struct cache_sb *sb)
{
	int fd;
	char uuid[40], set_uuid[40];

	if (sb->version > BCACHE_SB_MAX_VERSION) {
		printf("Must specify one of -C or -B\n");
		usage();
	}

	if ((sb->bucket_size & (sb->bucket_size - 1)) ||
	    (sb->block_size  & (sb->block_size - 1))) {
		printf("Block and bucket sizes must be powers of two\n");
		exit(EXIT_FAILURE);
	}

	if (sb->bucket_size < sb->block_size) {
		printf("Bad bucket size %i\n", sb->bucket_size);
		exit(EXIT_FAILURE);
	}

	if ((fd = open(dev, O_RDWR)) == -1) {
		printf("Can't open dev %s: %s\n", dev, strerror(errno));
		exit(EXIT_FAILURE);
	}

	sb->flags = 0;

	if (SB_BDEV(sb)) {
		SET_BDEV_WRITEBACK(sb, writeback);

		if (data_offset != 16) {
			sb->version = BCACHE_SB_BDEV_VERSION;
			sb->keys = 1;
			sb->d[0] = data_offset;
		}
	} else {
		SET_CACHE_DISCARD(sb, discard);
		SET_CACHE_REPLACEMENT(sb, cache_replacement_policy);
	}

	sb->offset		= SB_SECTOR;
	memcpy(sb->magic, bcache_magic, 16);
	sb->nbuckets		= getblocks(fd) / sb->bucket_size;
	sb->nr_in_set		= 1;
	sb->first_bucket	= (23 / sb->bucket_size) + 1;
	uuid_unparse(sb->uuid, uuid);
	uuid_unparse(sb->set_uuid, set_uuid);
	sb->csum = csum_set(sb);

	if (sb->nbuckets < 1 << 7) {
		printf("Not enough buckets: %ju, need %u\n",
		       sb->nbuckets, 1 << 7);
		exit(EXIT_FAILURE);
	}

	printf("UUID:			%s\n"
	       "Set UUID:		%s\n"
	       "nbuckets:		%ju\n"
	       "block_size:		%u\n"
	       "bucket_size:		%u\n"
	       "nr_in_set:		%u\n"
	       "nr_this_dev:		%u\n"
	       "first_bucket:		%u\n",
	       uuid, set_uuid,
	       sb->nbuckets,
	       sb->block_size,
	       sb->bucket_size,
	       sb->nr_in_set,
	       sb->nr_this_dev,
	       sb->first_bucket);

	if (pwrite(fd, sb, sizeof(*sb), SB_SECTOR << 9) != sizeof(*sb)) {
		perror("write error\n");
		exit(EXIT_FAILURE);
	}

	fsync(fd);
	close(fd);

	uuid_generate(sb->uuid);
}

int main(int argc, char **argv)
{
	bool written = false;
	int c;
	struct cache_sb sb;

	memset(&sb, 0, sizeof(struct cache_sb));
	sb.version = -1;
	sb.block_size = 8;
	sb.bucket_size = 1024;

	uuid_generate(sb.uuid);
	uuid_generate(sb.set_uuid);

	while ((c = getopt_long(argc, argv,
				"-hCBU:w:b:",
				opts, NULL)) != -1)
		switch (c) {
		case 'C':
			sb.version = 0;
			break;
		case 'B':
			sb.version = CACHE_BACKING_DEV;
			break;
		case 'b':
			sb.bucket_size = hatoi(optarg) / 512;
			break;
		case 'w':
			sb.block_size = hatoi(optarg) / 512;
			break;
		case 'U':
			if (uuid_parse(optarg, sb.uuid)) {
				printf("Bad uuid\n");
				exit(EXIT_FAILURE);
			}
			break;
		case 'p':
			cache_replacement_policy = read_string_list(optarg,
						    cache_replacement_policies);
			break;
		case 'o':
			data_offset = atoll(optarg);
			if (sb.d[0] < 16) {
				printf("Bad data offset; minimum 16 sectors\n");
				exit(EXIT_FAILURE);
			}
			break;
		case 'h':
			usage();
			break;
		case 1:
			write_sb(optarg, &sb);
			written = true;
			break;
		}

	if (!written) {
		printf("Please supply a device\n");
		usage();
	}

	return 0;
}