busybox/util-linux/mkfs_ext2.c

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/* vi: set sw=4 ts=4: */
/*
* mkfs_ext2: utility to create EXT2 filesystem
* inspired by genext2fs
*
* Busybox'ed (2009) by Vladimir Dronnikov <dronnikov@gmail.com>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//config:config MKE2FS
//config: bool "mke2fs (9.7 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: Utility to create EXT2 filesystems.
//config:
//config:config MKFS_EXT2
//config: bool "mkfs.ext2 (9.8 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: Alias to "mke2fs".
// APPLET_ODDNAME:name main location suid_type help
//applet:IF_MKE2FS( APPLET_ODDNAME(mke2fs, mkfs_ext2, BB_DIR_SBIN, BB_SUID_DROP, mkfs_ext2))
//applet:IF_MKFS_EXT2(APPLET_ODDNAME(mkfs.ext2, mkfs_ext2, BB_DIR_SBIN, BB_SUID_DROP, mkfs_ext2))
////////:IF_MKFS_EXT3(APPLET_ODDNAME(mkfs.ext3, mkfs_ext2, BB_DIR_SBIN, BB_SUID_DROP, mkfs_ext2))
//kbuild:lib-$(CONFIG_MKE2FS) += mkfs_ext2.o
//kbuild:lib-$(CONFIG_MKFS_EXT2) += mkfs_ext2.o
//usage:#define mkfs_ext2_trivial_usage
//usage: "[-Fn] "
/* //usage: "[-c|-l filename] " */
//usage: "[-b BLK_SIZE] "
/* //usage: "[-f fragment-size] [-g blocks-per-group] " */
//usage: "[-i INODE_RATIO] [-I INODE_SIZE] "
/* //usage: "[-j] [-J journal-options] [-N number-of-inodes] " */
//usage: "[-m RESERVED_PERCENT] "
/* //usage: "[-o creator-os] [-O feature[,...]] [-q] " */
/* //usage: "[r fs-revision-level] [-E extended-options] [-v] [-F] " */
//usage: "[-L LABEL] "
/* //usage: "[-M last-mounted-directory] [-S] [-T filesystem-type] " */
//usage: "BLOCKDEV [KBYTES]"
//usage:#define mkfs_ext2_full_usage "\n\n"
//usage: " -b BLK_SIZE Block size, bytes"
/* //usage: "\n -c Check device for bad blocks" */
/* //usage: "\n -E opts Set extended options" */
/* //usage: "\n -f size Fragment size in bytes" */
//usage: "\n -F Force"
/* //usage: "\n -g N Number of blocks in a block group" */
//usage: "\n -i RATIO Max number of files is filesystem_size / RATIO"
//usage: "\n -I BYTES Inode size (min 128)"
/* //usage: "\n -j Create a journal (ext3)" */
/* //usage: "\n -J opts Set journal options (size/device)" */
/* //usage: "\n -l file Read bad blocks list from file" */
//usage: "\n -L LBL Volume label"
//usage: "\n -m PERCENT Percent of blocks to reserve for admin"
/* //usage: "\n -M dir Set last mounted directory" */
//usage: "\n -n Dry run"
/* //usage: "\n -N N Number of inodes to create" */
/* //usage: "\n -o os Set the 'creator os' field" */
/* //usage: "\n -O features Dir_index/filetype/has_journal/journal_dev/sparse_super" */
/* //usage: "\n -q Quiet" */
/* //usage: "\n -r rev Set filesystem revision" */
/* //usage: "\n -S Write superblock and group descriptors only" */
/* //usage: "\n -T fs-type Set usage type (news/largefile/largefile4)" */
/* //usage: "\n -v Verbose" */
#include "libbb.h"
#include <linux/fs.h>
#include "bb_e2fs_defs.h"
#define ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT 0
#define ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX 1
#define EXT2_HASH_HALF_MD4 1
#define EXT2_FLAGS_SIGNED_HASH 0x0001
#define EXT2_FLAGS_UNSIGNED_HASH 0x0002
// storage helpers
char BUG_wrong_field_size(void);
#define STORE_LE(field, value) \
do { \
if (sizeof(field) == 4) \
field = SWAP_LE32((uint32_t)(value)); \
else if (sizeof(field) == 2) \
field = SWAP_LE16((uint16_t)(value)); \
else if (sizeof(field) == 1) \
field = (uint8_t)(value); \
else \
BUG_wrong_field_size(); \
} while (0)
#define FETCH_LE32(field) \
(sizeof(field) == 4 ? SWAP_LE32(field) : BUG_wrong_field_size())
// All fields are little-endian
struct ext2_dir {
uint32_t inode1;
uint16_t rec_len1;
uint8_t name_len1;
uint8_t file_type1;
char name1[4];
uint32_t inode2;
uint16_t rec_len2;
uint8_t name_len2;
uint8_t file_type2;
char name2[4];
uint32_t inode3;
uint16_t rec_len3;
uint8_t name_len3;
uint8_t file_type3;
char name3[12];
};
static unsigned int_log2(unsigned arg)
{
unsigned r = 0;
while ((arg >>= 1) != 0)
r++;
return r;
}
// taken from mkfs_minix.c. libbb candidate?
// "uint32_t size", since we never use it for anything >32 bits
static uint32_t div_roundup(uint32_t size, uint32_t n)
{
// Overflow-resistant
uint32_t res = size / n;
if (res * n != size)
res++;
return res;
}
static void allocate(uint8_t *bitmap, uint32_t blocksize, uint32_t start, uint32_t end)
{
uint32_t i;
//bb_error_msg("ALLOC: [%u][%u][%u]: [%u-%u]:=[%x],[%x]", blocksize, start, end, start/8, blocksize - end/8 - 1, (1 << (start & 7)) - 1, (uint8_t)(0xFF00 >> (end & 7)));
memset(bitmap, 0, blocksize);
i = start / 8;
memset(bitmap, 0xFF, i);
bitmap[i] = (1 << (start & 7)) - 1; //0..7 => 00000000..01111111
i = end / 8;
bitmap[blocksize - i - 1] |= 0x7F00 >> (end & 7); //0..7 => 00000000..11111110
memset(bitmap + blocksize - i, 0xFF, i); // N.B. no overflow here!
}
static uint32_t has_super(uint32_t x)
{
// 0, 1 and powers of 3, 5, 7 up to 2^32 limit
static const uint32_t supers[] = {
0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729,
2187, 2401, 3125, 6561, 15625, 16807, 19683, 59049, 78125,
117649, 177147, 390625, 531441, 823543, 1594323, 1953125,
4782969, 5764801, 9765625, 14348907, 40353607, 43046721,
48828125, 129140163, 244140625, 282475249, 387420489,
1162261467, 1220703125, 1977326743, 3486784401/* >2^31 */,
};
const uint32_t *sp = supers + ARRAY_SIZE(supers);
while (1) {
sp--;
if (x == *sp)
return 1;
if (x > *sp)
return 0;
}
}
#define fd 3 /* predefined output descriptor */
static void PUT(uint64_t off, void *buf, uint32_t size)
{
//bb_error_msg("PUT[%llu]:[%u]", off, size);
xlseek(fd, off, SEEK_SET);
xwrite(fd, buf, size);
}
// 128 and 256-byte inodes:
// 128-byte inode is described by struct ext2_inode.
// 256-byte one just has these fields appended:
// __u16 i_extra_isize;
// __u16 i_pad1;
// __u32 i_ctime_extra; /* extra Change time (nsec << 2 | epoch) */
// __u32 i_mtime_extra; /* extra Modification time (nsec << 2 | epoch) */
// __u32 i_atime_extra; /* extra Access time (nsec << 2 | epoch) */
// __u32 i_crtime; /* File creation time */
// __u32 i_crtime_extra; /* extra File creation time (nsec << 2 | epoch)*/
// __u32 i_version_hi; /* high 32 bits for 64-bit version */
// the rest is padding.
//
// linux/ext2_fs.h has "#define i_size_high i_dir_acl" which suggests that even
// 128-byte inode is capable of describing large files (i_dir_acl is meaningful
// only for directories, which never need i_size_high).
//
// Standard mke2fs creates a filesystem with 256-byte inodes if it is
// bigger than 0.5GB.
// Standard mke2fs 1.41.9:
// Usage: mke2fs [-c|-l filename] [-b block-size] [-f fragment-size]
// [-i bytes-per-inode] [-I inode-size] [-J journal-options]
// [-G meta group size] [-N number-of-inodes]
// [-m reserved-blocks-percentage] [-o creator-os]
// [-g blocks-per-group] [-L volume-label] [-M last-mounted-directory]
// [-O feature[,...]] [-r fs-revision] [-E extended-option[,...]]
// [-T fs-type] [-U UUID] [-jnqvFSV] device [blocks-count]
//
// Options not commented below are taken but silently ignored:
enum {
OPT_c = 1 << 0,
OPT_l = 1 << 1,
OPT_b = 1 << 2, // block size, in bytes
OPT_f = 1 << 3,
OPT_i = 1 << 4, // bytes per inode
OPT_I = 1 << 5, // custom inode size, in bytes
OPT_J = 1 << 6,
OPT_G = 1 << 7,
OPT_N = 1 << 8,
OPT_m = 1 << 9, // percentage of blocks reserved for superuser
OPT_o = 1 << 10,
OPT_g = 1 << 11,
OPT_L = 1 << 12, // label
OPT_M = 1 << 13,
OPT_O = 1 << 14,
OPT_r = 1 << 15,
OPT_E = 1 << 16,
OPT_T = 1 << 17,
OPT_U = 1 << 18,
OPT_j = 1 << 19,
OPT_n = 1 << 20, // dry run: do not write anything
OPT_q = 1 << 21,
OPT_v = 1 << 22,
OPT_F = 1 << 23,
OPT_S = 1 << 24,
//OPT_V = 1 << 25, // -V version. bbox applets don't support that
};
int mkfs_ext2_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
{
unsigned i, pos, n;
unsigned bs, bpi;
unsigned blocksize, blocksize_log2;
unsigned inodesize, user_inodesize;
unsigned reserved_percent = 5;
unsigned long long kilobytes;
uint32_t nblocks, nblocks_full;
uint32_t nreserved;
uint32_t ngroups;
uint32_t bytes_per_inode;
uint32_t first_block;
uint32_t inodes_per_group;
uint32_t group_desc_blocks;
uint32_t inode_table_blocks;
uint32_t lost_and_found_blocks;
time_t timestamp;
const char *label = "";
struct stat st;
struct ext2_super_block *sb; // superblock
struct ext2_group_desc *gd; // group descriptors
struct ext2_inode *inode;
struct ext2_dir *dir;
uint8_t *buf;
// using global "option_mask32" instead of local "opts":
// we are register starved here
/*opts =*/ getopt32(argv, "cl:b:+f:i:+I:+J:G:N:m:+o:g:L:M:O:r:E:T:U:jnqvFS",
/*lbfi:*/ NULL, &bs, NULL, &bpi,
/*IJGN:*/ &user_inodesize, NULL, NULL, NULL,
/*mogL:*/ &reserved_percent, NULL, NULL, &label,
/*MOrE:*/ NULL, NULL, NULL, NULL,
/*TU:*/ NULL, NULL);
argv += optind; // argv[0] -- device
// open the device, check the device is a block device
xmove_fd(xopen(argv[0], O_WRONLY), fd);
xfstat(fd, &st, argv[0]);
if (!S_ISBLK(st.st_mode) && !(option_mask32 & OPT_F))
bb_error_msg_and_die("%s: not a block device", argv[0]);
// check if it is mounted
// N.B. what if we format a file? find_mount_point will return false negative since
// it is loop block device which is mounted!
if (find_mount_point(argv[0], 0))
bb_error_msg_and_die("can't format mounted filesystem");
// get size in kbytes
kilobytes = get_volume_size_in_bytes(fd, argv[1], 1024, /*extend:*/ !(option_mask32 & OPT_n)) / 1024;
bytes_per_inode = 16384;
if (kilobytes < 512*1024)
bytes_per_inode = 4096;
if (kilobytes < 3*1024)
bytes_per_inode = 8192;
if (option_mask32 & OPT_i)
bytes_per_inode = bpi;
// Determine block size and inode size
// block size is a multiple of 1024
// inode size is a multiple of 128
blocksize = 1024;
inodesize = sizeof(struct ext2_inode); // 128
if (kilobytes >= 512*1024) { // mke2fs 1.41.9 compat
blocksize = 4096;
inodesize = 256;
}
if (EXT2_MAX_BLOCK_SIZE > 4096) {
// kilobytes >> 22 == size in 4gigabyte chunks.
// if size >= 16k gigs, blocksize must be increased.
// Try "mke2fs -F image $((16 * 1024*1024*1024))"
while ((kilobytes >> 22) >= blocksize)
blocksize *= 2;
}
if (option_mask32 & OPT_b)
blocksize = bs;
if (blocksize < EXT2_MIN_BLOCK_SIZE
|| blocksize > EXT2_MAX_BLOCK_SIZE
|| (blocksize & (blocksize - 1)) // not power of 2
) {
bb_error_msg_and_die("blocksize %u is bad", blocksize);
}
// Do we have custom inode size?
if (option_mask32 & OPT_I) {
if (user_inodesize < sizeof(*inode)
|| user_inodesize > blocksize
|| (user_inodesize & (user_inodesize - 1)) // not power of 2
) {
bb_error_msg("-%c is bad", 'I');
} else {
inodesize = user_inodesize;
}
}
if ((int32_t)bytes_per_inode < blocksize)
bb_error_msg_and_die("-%c is bad", 'i');
// number of bits in one block, i.e. 8*blocksize
#define blocks_per_group (8 * blocksize)
first_block = (EXT2_MIN_BLOCK_SIZE == blocksize);
blocksize_log2 = int_log2(blocksize);
// Determine number of blocks
kilobytes >>= (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
nblocks = kilobytes;
if (nblocks != kilobytes)
bb_error_msg_and_die("block count doesn't fit in 32 bits");
#define kilobytes kilobytes_unused_after_this
// Experimentally, standard mke2fs won't work on images smaller than 60k
if (nblocks < 60)
bb_error_msg_and_die("need >= 60 blocks");
// How many reserved blocks?
if (reserved_percent > 50)
bb_error_msg_and_die("-%c is bad", 'm');
nreserved = (uint64_t)nblocks * reserved_percent / 100;
// N.B. killing e2fsprogs feature! Unused blocks don't account in calculations
nblocks_full = nblocks;
// If last block group is too small, nblocks may be decreased in order
// to discard it, and control returns here to recalculate some
// parameters.
// Note: blocksize and bytes_per_inode are never recalculated.
retry:
// N.B. a block group can have no more than blocks_per_group blocks
ngroups = div_roundup(nblocks - first_block, blocks_per_group);
group_desc_blocks = div_roundup(ngroups, blocksize / sizeof(*gd));
// TODO: reserved blocks must be marked as such in the bitmaps,
// or resulting filesystem is corrupt
if (ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT) {
/*
* From e2fsprogs: Calculate the number of GDT blocks to reserve for online
* filesystem growth.
* The absolute maximum number of GDT blocks we can reserve is determined by
* the number of block pointers that can fit into a single block.
* We set it at 1024x the current filesystem size, or
* the upper block count limit (2^32), whichever is lower.
*/
uint32_t reserved_group_desc_blocks = 0xFFFFFFFF; // maximum block number
if (nblocks < reserved_group_desc_blocks / 1024)
reserved_group_desc_blocks = nblocks * 1024;
reserved_group_desc_blocks = div_roundup(reserved_group_desc_blocks - first_block, blocks_per_group);
reserved_group_desc_blocks = div_roundup(reserved_group_desc_blocks, blocksize / sizeof(*gd)) - group_desc_blocks;
if (reserved_group_desc_blocks > blocksize / sizeof(uint32_t))
reserved_group_desc_blocks = blocksize / sizeof(uint32_t);
//TODO: STORE_LE(sb->s_reserved_gdt_blocks, reserved_group_desc_blocks);
group_desc_blocks += reserved_group_desc_blocks;
}
{
// N.B. e2fsprogs does as follows!
uint32_t overhead, remainder;
// ninodes is the max number of inodes in this filesystem
uint32_t ninodes = ((uint64_t) nblocks_full * blocksize) / bytes_per_inode;
if (ninodes < EXT2_GOOD_OLD_FIRST_INO+1)
ninodes = EXT2_GOOD_OLD_FIRST_INO+1;
inodes_per_group = div_roundup(ninodes, ngroups);
// minimum number because the first EXT2_GOOD_OLD_FIRST_INO-1 are reserved
if (inodes_per_group < 16)
inodes_per_group = 16;
// a block group can't have more inodes than blocks
if (inodes_per_group > blocks_per_group)
inodes_per_group = blocks_per_group;
// adjust inodes per group so they completely fill the inode table blocks in the descriptor
inodes_per_group = (div_roundup(inodes_per_group * inodesize, blocksize) * blocksize) / inodesize;
// make sure the number of inodes per group is a multiple of 8
inodes_per_group &= ~7;
inode_table_blocks = div_roundup(inodes_per_group * inodesize, blocksize);
// to be useful, lost+found should occupy at least 2 blocks (but not exceeding 16*1024 bytes),
// and at most EXT2_NDIR_BLOCKS. So reserve these blocks right now
/* Or e2fsprogs comment verbatim (what does it mean?):
* Ensure that lost+found is at least 2 blocks, so we always
* test large empty blocks for big-block filesystems. */
lost_and_found_blocks = MIN(EXT2_NDIR_BLOCKS, 16 >> (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE));
// the last group needs more attention: isn't it too small for possible overhead?
overhead = (has_super(ngroups - 1) ? (1/*sb*/ + group_desc_blocks) : 0) + 1/*bbmp*/ + 1/*ibmp*/ + inode_table_blocks;
remainder = (nblocks - first_block) % blocks_per_group;
////can't happen, nblocks >= 60 guarantees this
////if ((1 == ngroups)
//// && remainder
//// && (remainder < overhead + 1/* "/" */ + lost_and_found_blocks)
////) {
//// bb_error_msg_and_die("way small device");
////}
// Standard mke2fs uses 50. Looks like a bug in our calculation
// of "remainder" or "overhead" - we don't match standard mke2fs
// when we transition from one group to two groups
// (a bit after 8M image size), but it works for two->three groups
// transition (at 16M).
if (remainder && (remainder < overhead + 50)) {
//bb_error_msg("CHOP[%u]", remainder);
nblocks -= remainder;
goto retry;
}
}
if (nblocks_full - nblocks)
printf("warning: %u blocks unused\n\n", nblocks_full - nblocks);
printf(
"Filesystem label=%s\n"
"OS type: Linux\n"
"Block size=%u (log=%u)\n"
"Fragment size=%u (log=%u)\n"
"%u inodes, %u blocks\n"
"%u blocks (%u%%) reserved for the super user\n"
"First data block=%u\n"
"Maximum filesystem blocks=%u\n"
"%u block groups\n"
"%u blocks per group, %u fragments per group\n"
"%u inodes per group"
, label
, blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
, blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
, inodes_per_group * ngroups, nblocks
, nreserved, reserved_percent
, first_block
, group_desc_blocks * (blocksize / (unsigned)sizeof(*gd)) * blocks_per_group
, ngroups
, blocks_per_group, blocks_per_group
, inodes_per_group
);
{
const char *fmt = "\nSuperblock backups stored on blocks:\n"
"\t%u";
pos = first_block;
for (i = 1; i < ngroups; i++) {
pos += blocks_per_group;
if (has_super(i)) {
printf(fmt, (unsigned)pos);
fmt = ", %u";
}
}
}
bb_putchar('\n');
if (option_mask32 & OPT_n) {
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
return EXIT_SUCCESS;
}
// TODO: 3/5 refuse if mounted
// TODO: 4/5 compat options
// TODO: 1/5 sanity checks
// TODO: 0/5 more verbose error messages
// TODO: 4/5 bigendianness: recheck, wait for ARM reporters
// TODO: 2/5 reserved GDT: how to mark but not allocate?
// TODO: 3/5 dir_index?
// fill the superblock
sb = xzalloc(1024);
STORE_LE(sb->s_rev_level, EXT2_DYNAMIC_REV); // revision 1 filesystem
STORE_LE(sb->s_magic, EXT2_SUPER_MAGIC);
STORE_LE(sb->s_inode_size, inodesize);
// set "Required extra isize" and "Desired extra isize" fields to 28
if (inodesize != sizeof(*inode)) {
STORE_LE(sb->s_min_extra_isize, 0x001c);
STORE_LE(sb->s_want_extra_isize, 0x001c);
}
STORE_LE(sb->s_first_ino, EXT2_GOOD_OLD_FIRST_INO);
STORE_LE(sb->s_log_block_size, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
STORE_LE(sb->s_log_frag_size, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
// first 1024 bytes of the device are for boot record. If block size is 1024 bytes, then
// the first block is 1, otherwise 0
STORE_LE(sb->s_first_data_block, first_block);
// block and inode bitmaps occupy no more than one block, so maximum number of blocks is
STORE_LE(sb->s_blocks_per_group, blocks_per_group);
STORE_LE(sb->s_frags_per_group, blocks_per_group);
// blocks
STORE_LE(sb->s_blocks_count, nblocks);
// reserve blocks for superuser
STORE_LE(sb->s_r_blocks_count, nreserved);
// ninodes
STORE_LE(sb->s_inodes_per_group, inodes_per_group);
STORE_LE(sb->s_inodes_count, inodes_per_group * ngroups);
STORE_LE(sb->s_free_inodes_count, inodes_per_group * ngroups - EXT2_GOOD_OLD_FIRST_INO);
// timestamps
timestamp = time(NULL);
STORE_LE(sb->s_mkfs_time, timestamp);
STORE_LE(sb->s_wtime, timestamp);
STORE_LE(sb->s_lastcheck, timestamp);
// misc. Values are chosen to match mke2fs 1.41.9
STORE_LE(sb->s_state, 1); // TODO: what's 1?
STORE_LE(sb->s_creator_os, EXT2_OS_LINUX);
STORE_LE(sb->s_checkinterval, 24*60*60 * 180); // 180 days
STORE_LE(sb->s_errors, EXT2_ERRORS_DEFAULT);
// mke2fs 1.41.9 also sets EXT3_FEATURE_COMPAT_RESIZE_INODE
// and if >= 0.5GB, EXT3_FEATURE_RO_COMPAT_LARGE_FILE.
// we use values which match "mke2fs -O ^resize_inode":
// in this case 1.41.9 never sets EXT3_FEATURE_RO_COMPAT_LARGE_FILE.
STORE_LE(sb->s_feature_compat, EXT2_FEATURE_COMPAT_SUPP
| (EXT2_FEATURE_COMPAT_RESIZE_INO * ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT)
| (EXT2_FEATURE_COMPAT_DIR_INDEX * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX)
);
STORE_LE(sb->s_feature_incompat, EXT2_FEATURE_INCOMPAT_FILETYPE);
STORE_LE(sb->s_feature_ro_compat, EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER);
STORE_LE(sb->s_flags, EXT2_FLAGS_UNSIGNED_HASH * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX);
generate_uuid(sb->s_uuid);
if (ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX) {
STORE_LE(sb->s_def_hash_version, EXT2_HASH_HALF_MD4);
generate_uuid((uint8_t *)sb->s_hash_seed);
}
/*
* From e2fsprogs: add "jitter" to the superblock's check interval so that we
* don't check all the filesystems at the same time. We use a
* kludgy hack of using the UUID to derive a random jitter value.
*/
STORE_LE(sb->s_max_mnt_count,
EXT2_DFL_MAX_MNT_COUNT
+ (sb->s_uuid[ARRAY_SIZE(sb->s_uuid)-1] % EXT2_DFL_MAX_MNT_COUNT));
// write the label
safe_strncpy((char *)sb->s_volume_name, label, sizeof(sb->s_volume_name));
// calculate filesystem skeleton structures
gd = xzalloc(group_desc_blocks * blocksize);
buf = xmalloc(blocksize);
sb->s_free_blocks_count = 0;
for (i = 0, pos = first_block, n = nblocks - first_block;
i < ngroups;
i++, pos += blocks_per_group, n -= blocks_per_group
) {
uint32_t overhead = pos + (has_super(i) ? (1/*sb*/ + group_desc_blocks) : 0);
uint32_t free_blocks;
// fill group descriptors
STORE_LE(gd[i].bg_block_bitmap, overhead + 0);
STORE_LE(gd[i].bg_inode_bitmap, overhead + 1);
STORE_LE(gd[i].bg_inode_table, overhead + 2);
overhead = overhead - pos + 1/*bbmp*/ + 1/*ibmp*/ + inode_table_blocks;
gd[i].bg_free_inodes_count = inodes_per_group;
//STORE_LE(gd[i].bg_used_dirs_count, 0);
// N.B. both "/" and "/lost+found" are within the first block group
// "/" occupies 1 block, "/lost+found" occupies lost_and_found_blocks...
if (0 == i) {
// ... thus increased overhead for the first block group ...
overhead += 1 + lost_and_found_blocks;
// ... and 2 used directories
STORE_LE(gd[i].bg_used_dirs_count, 2);
// well known reserved inodes belong to the first block too
gd[i].bg_free_inodes_count -= EXT2_GOOD_OLD_FIRST_INO;
}
// cache free block count of the group
free_blocks = (n < blocks_per_group ? n : blocks_per_group) - overhead;
// mark preallocated blocks as allocated
//bb_error_msg("ALLOC: [%u][%u][%u]", blocksize, overhead, blocks_per_group - (free_blocks + overhead));
allocate(buf, blocksize,
// reserve "overhead" blocks
overhead,
// mark unused trailing blocks
blocks_per_group - (free_blocks + overhead)
);
// dump block bitmap
PUT((uint64_t)(FETCH_LE32(gd[i].bg_block_bitmap)) * blocksize, buf, blocksize);
STORE_LE(gd[i].bg_free_blocks_count, free_blocks);
// mark preallocated inodes as allocated
allocate(buf, blocksize,
// mark reserved inodes
inodes_per_group - gd[i].bg_free_inodes_count,
// mark unused trailing inodes
blocks_per_group - inodes_per_group
);
// dump inode bitmap
//PUT((uint64_t)(FETCH_LE32(gd[i].bg_block_bitmap)) * blocksize, buf, blocksize);
//but it's right after block bitmap, so we can just:
xwrite(fd, buf, blocksize);
STORE_LE(gd[i].bg_free_inodes_count, gd[i].bg_free_inodes_count);
// count overall free blocks
sb->s_free_blocks_count += free_blocks;
}
STORE_LE(sb->s_free_blocks_count, sb->s_free_blocks_count);
// dump filesystem skeleton structures
// printf("Writing superblocks and filesystem accounting information: ");
for (i = 0, pos = first_block; i < ngroups; i++, pos += blocks_per_group) {
// dump superblock and group descriptors and their backups
if (has_super(i)) {
// N.B. 1024 byte blocks are special
PUT(((uint64_t)pos * blocksize) + ((0 == i && 1024 != blocksize) ? 1024 : 0),
sb, 1024);
PUT(((uint64_t)pos * blocksize) + blocksize,
gd, group_desc_blocks * blocksize);
}
}
// zero boot sectors
memset(buf, 0, blocksize);
// Disabled: standard mke2fs doesn't do this, and
// on SPARC this destroys Sun disklabel.
// Users who need/want zeroing can easily do it with dd.
//PUT(0, buf, 1024); // N.B. 1024 <= blocksize, so buf[0..1023] contains zeros
// zero inode tables
for (i = 0; i < ngroups; ++i)
for (n = 0; n < inode_table_blocks; ++n)
PUT((uint64_t)(FETCH_LE32(gd[i].bg_inode_table) + n) * blocksize,
buf, blocksize);
// prepare directory inode
inode = (struct ext2_inode *)buf;
STORE_LE(inode->i_mode, S_IFDIR | S_IRWXU | S_IRGRP | S_IROTH | S_IXGRP | S_IXOTH);
STORE_LE(inode->i_mtime, timestamp);
STORE_LE(inode->i_atime, timestamp);
STORE_LE(inode->i_ctime, timestamp);
STORE_LE(inode->i_size, blocksize);
// inode->i_blocks stores the number of 512 byte data blocks
// (512, because it goes directly to struct stat without scaling)
STORE_LE(inode->i_blocks, blocksize / 512);
// dump root dir inode
STORE_LE(inode->i_links_count, 3); // "/.", "/..", "/lost+found/.." point to this inode
STORE_LE(inode->i_block[0], FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks);
PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_ROOT_INO-1) * inodesize,
buf, inodesize);
// dump lost+found dir inode
STORE_LE(inode->i_links_count, 2); // both "/lost+found" and "/lost+found/." point to this inode
STORE_LE(inode->i_size, lost_and_found_blocks * blocksize);
STORE_LE(inode->i_blocks, (lost_and_found_blocks * blocksize) / 512);
n = FETCH_LE32(inode->i_block[0]) + 1;
for (i = 0; i < lost_and_found_blocks; ++i)
STORE_LE(inode->i_block[i], i + n); // use next block
//bb_error_msg("LAST BLOCK USED[%u]", i + n);
PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_GOOD_OLD_FIRST_INO-1) * inodesize,
buf, inodesize);
// dump directories
memset(buf, 0, blocksize);
dir = (struct ext2_dir *)buf;
// dump 2nd+ blocks of "/lost+found"
STORE_LE(dir->rec_len1, blocksize); // e2fsck 1.41.4 compat (1.41.9 does not need this)
for (i = 1; i < lost_and_found_blocks; ++i)
PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 1+i) * blocksize,
buf, blocksize);
// dump 1st block of "/lost+found"
STORE_LE(dir->inode1, EXT2_GOOD_OLD_FIRST_INO);
STORE_LE(dir->rec_len1, 12);
STORE_LE(dir->name_len1, 1);
STORE_LE(dir->file_type1, EXT2_FT_DIR);
dir->name1[0] = '.';
STORE_LE(dir->inode2, EXT2_ROOT_INO);
STORE_LE(dir->rec_len2, blocksize - 12);
STORE_LE(dir->name_len2, 2);
STORE_LE(dir->file_type2, EXT2_FT_DIR);
dir->name2[0] = '.'; dir->name2[1] = '.';
PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 1) * blocksize, buf, blocksize);
// dump root dir block
STORE_LE(dir->inode1, EXT2_ROOT_INO);
STORE_LE(dir->rec_len2, 12);
STORE_LE(dir->inode3, EXT2_GOOD_OLD_FIRST_INO);
STORE_LE(dir->rec_len3, blocksize - 12 - 12);
STORE_LE(dir->name_len3, 10);
STORE_LE(dir->file_type3, EXT2_FT_DIR);
strcpy(dir->name3, "lost+found");
PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 0) * blocksize, buf, blocksize);
// cleanup
if (ENABLE_FEATURE_CLEAN_UP) {
free(buf);
free(gd);
free(sb);
}
xclose(fd);
return EXIT_SUCCESS;
}