mirror of http://dave.jikos.cz/fix-dev-count.c. thanks!

fix-dev-count.c

/*
 * One-time fix for mismatch of devices after a failed mount with message like
 *
 * BTRFS error (device sde): super_num_devices 7 mismatch with num_devices 6 found here
 *
 * Compile:
 *    gcc -o fix-dev-count fix-dev-count.c
 *
 * Run:
 *    ./fix-dev-count /dev/sdx <number>
 *
 * where sdx is your devices and <number> is the value from the error message,
 * in this case 6.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <inttypes.h>
#include <string.h>

#define BLOCKSIZE (4096)
static char buf[BLOCKSIZE];
static int csum_size;

typedef unsigned int u32;
typedef unsigned int __le32;
typedef unsigned short int __le16;
typedef unsigned long long __le64;
typedef unsigned long long u64;
typedef unsigned char u8;

#define BTRFS_FSID_SIZE 16
#define BTRFS_UUID_SIZE 16
#define BTRFS_CSUM_SIZE 32
#define BTRFS_SUPER_INFO_OFFSET (64 * 1024)
#define BTRFS_SUPER_INFO_SIZE 4096
#define BTRFS_CSUM_TYPE_CRC32	0
static int btrfs_csum_sizes[] = { 4 };

#if __BYTE_ORDER == __BIG_ENDIAN
#define cpu_to_le64(x) ((__le64)(u64)(bswap_64(x)))
#define le64_to_cpu(x) ((u64)(__le64)(bswap_64(x)))
#define cpu_to_le32(x) ((__le32)(u32)(bswap_32(x)))
#define le32_to_cpu(x) ((u32)(__le32)(bswap_32(x)))
#else
#define cpu_to_le64(x) ((__le64)(u64)(x))
#define le64_to_cpu(x) ((u64)(__le64)(x))
#define cpu_to_le32(x) ((__le32)(u32)(x))
#define le32_to_cpu(x) ((u32)(__le32)(x))
#endif

#define get_unaligned_le32(p) le32_to_cpu(((const struct __una_u32 *)(p))->x)
#define put_unaligned_le32(val,p) (((struct __una_u32 *)(p))->x = cpu_to_le32(val))
struct __una_u32 { u32 x; } __attribute__((__packed__));
#define get_unaligned_le64(p) le64_to_cpu(((const struct __una_u64 *)(p))->x)
#define put_unaligned_le64(val,p) (((struct __una_u64 *)(p))->x = cpu_to_le64(val))
struct __una_u64 { u64 x; } __attribute__((__packed__));

u32 crc32c_le(u32 seed, unsigned char const *data, size_t length);
void crc32c_optimization_init(void);

#define crc32c(seed, data, length) crc32c_le(seed, (unsigned char const *)data, length)
#define btrfs_crc32c crc32c

/* crc32.c */
u32 __crc32c_le(u32 crc, unsigned char const *data, size_t length);
static u32 (*crc_function)(u32 crc, unsigned char const *data, size_t length) = __crc32c_le;

static const u32 crc32c_table[256] = {
	0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
	0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
	0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
	0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
	0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
	0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
	0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
	0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
	0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
	0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
	0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
	0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
	0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
	0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
	0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
	0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
	0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
	0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
	0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
	0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
	0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
	0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
	0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
	0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
	0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
	0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
	0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
	0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
	0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
	0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
	0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
	0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
	0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
	0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
	0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
	0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
	0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
	0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
	0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
	0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
	0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
	0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
	0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
	0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
	0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
	0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
	0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
	0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
	0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
	0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
	0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
	0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
	0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
	0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
	0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
	0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
	0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
	0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
	0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
	0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
	0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
	0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
	0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
	0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
};

u32 __crc32c_le(u32 crc, unsigned char const *data, size_t length)
{
	while (length--)
		crc =
		    crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8);
	return crc;
}

u32 crc32c_le(u32 crc, unsigned char const *data, size_t length)
{
	return crc_function(crc, data, length);
}

/* crc32.c EOF*/

struct btrfs_super_block {
	char csum[BTRFS_CSUM_SIZE];
	char fsid[BTRFS_FSID_SIZE];
	__le64 bytenr;
	__le64 flags;
	__le64 magic;
	__le64 generation;
	__le64 root;
	__le64 chunk_root;
	__le64 log_root;
	__le64 log_root_transid;
	__le64 total_bytes;
	__le64 bytes_used;
	__le64 root_dir_objectid;
	__le64 num_devices;
	__le32 sectorsize;
	__le32 nodesize;
	__le32 leafsize;
	__le32 stripesize;
	__le32 sys_chunk_array_size;
	__le64 chunk_root_generation;
	__le64 compat_flags;
	__le64 compat_ro_flags;
	__le64 incompat_flags;
	__le16 csum_type;
	u8 root_level;
	u8 chunk_root_level;
	u8 log_root_level;
	/*
	struct btrfs_dev_item dev_item;
	char label[BTRFS_LABEL_SIZE];
	__le64 cache_generation;
	__le64 reserved[31];
	u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
	*/
} __attribute__ ((__packed__));

struct btrfs_header {
	u8 csum[BTRFS_CSUM_SIZE];
	u8 fsid[BTRFS_FSID_SIZE];
	__le64 bytenr;
	__le64 flags;

	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
	__le64 generation;
	__le64 owner;
	__le32 nritems;
	u8 level;
} __attribute__ ((__packed__));

u32 btrfs_csum_data(char *data, u32 seed, size_t len)
{
	return crc32c(seed, data, len);
}

void btrfs_csum_final(u32 crc, char *result)
{
	put_unaligned_le32(~crc, result);
}

static int check_csum_superblock(void *sb)
{
	char result[csum_size];
	u32 crc = ~(u32)0;

	crc = btrfs_csum_data((char *)sb + BTRFS_CSUM_SIZE,
				crc, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
	btrfs_csum_final(crc, result);

	return !memcmp(sb, &result, csum_size);
}

static void update_block_csum(void *block, int is_sb)
{
	char result[csum_size];
	struct btrfs_header *hdr;
	u32 crc = ~(u32)0;

	if (is_sb) {
		crc = btrfs_csum_data((char *)block + BTRFS_CSUM_SIZE, crc,
				BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
	} else {
		crc = btrfs_csum_data((char *)block + BTRFS_CSUM_SIZE, crc,
				BLOCKSIZE - BTRFS_CSUM_SIZE);
	}
	btrfs_csum_final(crc, result);
	memset(block, 0, BTRFS_CSUM_SIZE);
	hdr = (struct btrfs_header *)block;
	memcpy(&hdr->csum, result, csum_size);
}

int main(int argc, char **argv) {
	int fd;
	loff_t off;
	loff_t fsize;
	struct stat st;
	int ret;
	struct btrfs_header *hdr;
	int devcount;
	struct btrfs_super_block *sb;

	if (argc <= 2) {
		printf("Usage: %s image number\n", argv[0]);
		exit(1);
	}
	fd = open(argv[1], O_RDWR | O_EXCL);
	if (fd == -1) {
		perror("open()");
		exit(1);
	}
	devcount = atoi(argv[2]);

	/* verify superblock */
	csum_size = btrfs_csum_sizes[BTRFS_CSUM_TYPE_CRC32];
	fstat(fd, &st);
	fsize = st.st_size;
	off = BTRFS_SUPER_INFO_OFFSET;

	ret = pread(fd, buf, BLOCKSIZE, off);
	if (ret <= 0) {
		printf("pread error %d at offset %llu\n",
				ret, (unsigned long long)off);
		exit(1);
	}
	if (ret != BLOCKSIZE) {
		printf("pread error at offset %llu: read only %d bytes\n",
				(unsigned long long)off, ret);
		exit(1);
	}
	hdr = (struct btrfs_header *)buf;
	/* verify checksum */
	if (!check_csum_superblock(&hdr->csum)) {
		printf("super block checksum does not match at offset %llu, will be corrected\n",
				(unsigned long long)off);
	} else {
		printf("super block checksum is ok\n");
	}
	sb = (struct btrfs_super_block *)buf;
	ret = le64_to_cpu(sb->num_devices);
	printf("Found devices %d\n", ret);
	printf("Set devices to %d\n", devcount);
	sb->num_devices = cpu_to_le64(devcount);
	printf("Update csum\n");
	update_block_csum(buf, 1);
	ret = pwrite(fd, buf, BLOCKSIZE, off);
	if (ret <= 0) {
		printf("pwrite error %d at offset %llu\n",
				ret, (unsigned long long)off);
		exit(1);
	}
	if (ret != BLOCKSIZE) {
		printf("pwrite error at offset %llu: written only %d bytes\n",
				(unsigned long long)off, ret);
		exit(1);
	}
	fsync(fd);
	close(fd);
	return 0;
}