1 /* vi: set sw=4 ts=4: */
3 * mkfs_ext2: utility to create EXT2 filesystem
4 * inspired by genext2fs
6 * Busybox'ed (2009) by Vladimir Dronnikov <dronnikov@gmail.com>
8 * Licensed under GPLv2, see file LICENSE in this tarball for details.
12 #include <linux/ext2_fs.h>
13 #include <sys/user.h> /* PAGE_SIZE */
15 # define PAGE_SIZE 4096
17 #include "volume_id/volume_id_internal.h"
19 #define ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT 0
20 #define ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX 1
23 #define s_reserved_gdt_blocks s_padding1
24 #define s_mkfs_time s_reserved[0]
25 #define s_flags s_reserved[22]
26 #define EXT2_HASH_HALF_MD4 1
27 #define EXT2_FLAGS_SIGNED_HASH 0x0001
29 // whiteout: for writable overlays
30 //#define LINUX_S_IFWHT 0160000
31 //#define EXT2_FEATURE_INCOMPAT_WHITEOUT 0x0020
34 char BUG_wrong_field_size(void);
35 #define STORE_LE(field, value) \
37 if (sizeof(field) == 4) \
38 field = cpu_to_le32(value); \
39 else if (sizeof(field) == 2) \
40 field = cpu_to_le16(value); \
41 else if (sizeof(field) == 1) \
44 BUG_wrong_field_size(); \
47 #define FETCH_LE32(field) \
48 (sizeof(field) == 4 ? cpu_to_le32(field) : BUG_wrong_field_size())
50 // All fields are little-endian
69 static unsigned int_log2(unsigned arg)
72 while ((arg >>= 1) != 0)
77 // taken from mkfs_minix.c. libbb candidate?
78 // "uint32_t size", since we never use it for anything >32 bits
79 static uint32_t div_roundup(uint32_t size, uint32_t n)
82 uint32_t res = size / n;
88 static void allocate(uint8_t *bitmap, uint32_t blocksize, uint32_t start, uint32_t end)
92 //bb_info_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)));
93 memset(bitmap, 0, blocksize);
95 memset(bitmap, 0xFF, i);
96 bitmap[i] = (1 << (start & 7)) - 1; //0..7 => 00000000..01111111
98 bitmap[blocksize - i - 1] |= 0x7F00 >> (end & 7); //0..7 => 00000000..11111110
99 memset(bitmap + blocksize - i, 0xFF, i); // N.B. no overflow here!
102 static uint32_t has_super(uint32_t x)
104 // 0, 1 and powers of 3, 5, 7 up to 2^32 limit
105 static const uint32_t supers[] = {
106 0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729,
107 2187, 2401, 3125, 6561, 15625, 16807, 19683, 59049, 78125,
108 117649, 177147, 390625, 531441, 823543, 1594323, 1953125,
109 4782969, 5764801, 9765625, 14348907, 40353607, 43046721,
110 48828125, 129140163, 244140625, 282475249, 387420489,
111 1162261467, 1220703125, 1977326743, 3486784401/* >2^31 */,
113 const uint32_t *sp = supers + ARRAY_SIZE(supers);
123 /* Standard mke2fs 1.41.9:
124 * Usage: mke2fs [-c|-l filename] [-b block-size] [-f fragment-size]
125 * [-i bytes-per-inode] [-I inode-size] [-J journal-options]
126 * [-G meta group size] [-N number-of-inodes]
127 * [-m reserved-blocks-percentage] [-o creator-os]
128 * [-g blocks-per-group] [-L volume-label] [-M last-mounted-directory]
129 * [-O feature[,...]] [-r fs-revision] [-E extended-option[,...]]
130 * [-T fs-type] [-U UUID] [-jnqvFSV] device [blocks-count]
132 // N.B. not commented below options are taken and silently ignored
136 OPT_b = 1 << 2, // block size, in bytes
138 OPT_i = 1 << 4, // bytes per inode
143 OPT_m = 1 << 9, // percentage of blocks reserved for superuser
146 OPT_L = 1 << 12, // label
154 OPT_n = 1 << 20, // dry run: do not write anything
159 //OPT_V = 1 << 25, // -V version. bbox applets don't support that
162 #define fd 3 /* predefined output descriptor */
164 static void PUT(uint64_t off, void *buf, uint32_t size)
166 // bb_info_msg("PUT[%llu]:[%u]", off, size);
167 xlseek(fd, off, SEEK_SET);
168 xwrite(fd, buf, size);
171 int mkfs_ext2_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
172 int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
176 unsigned blocksize, blocksize_log2;
177 unsigned reserved_percent = 5;
178 unsigned long long kilobytes;
179 uint32_t nblocks, nblocks_full;
182 uint32_t bytes_per_inode;
183 uint32_t first_block;
184 uint32_t inodes_per_group;
185 uint32_t group_desc_blocks;
186 uint32_t inode_table_blocks;
187 uint32_t lost_and_found_blocks;
190 const char *label = "";
192 struct ext2_super_block *sb; // superblock
193 struct ext2_group_desc *gd; // group descriptors
194 struct ext2_inode *inode;
195 struct ext2_dir *dir;
198 opt_complementary = "-1:b+:m+:i+";
199 opts = getopt32(argv, "cl:b:f:i:I:J:G:N:m:o:g:L:M:O:r:E:T:U:jnqvFS",
200 NULL, &bs, NULL, &bpi, NULL, NULL, NULL, NULL,
201 &reserved_percent, NULL, NULL, &label, NULL, NULL, NULL, NULL, NULL, NULL);
202 argv += optind; // argv[0] -- device
204 // check the device is a block device
205 xmove_fd(xopen(argv[0], O_WRONLY), fd);
207 if (!S_ISBLK(st.st_mode) && !(opts & OPT_F))
208 bb_error_msg_and_die("not a block device");
210 // check if it is mounted
211 // N.B. what if we format a file? find_mount_point will return false negative since
212 // it is loop block device which mounted!
213 if (find_mount_point(argv[0], 0))
214 bb_error_msg_and_die("can't format mounted filesystem");
216 // open the device, get size in kbytes
218 kilobytes = xatoull(argv[1]);
220 kilobytes = (uoff_t)xlseek(fd, 0, SEEK_END) / 1024;
223 bytes_per_inode = 16384;
224 if (kilobytes < 512*1024)
225 bytes_per_inode = 4096;
226 if (kilobytes < 3*1024)
227 bytes_per_inode = 8192;
229 bytes_per_inode = bpi;
231 // Determine block size
232 // block size is a multiple of 1024
234 if (kilobytes >= 512*1024) // mke2fs 1.41.9 compat
236 if (EXT2_MAX_BLOCK_SIZE > 4096) {
237 // kilobytes >> 22 == size in 4gigabyte chunks.
238 // if size >= 16k gigs, blocksize must be increased.
239 // Try "mke2fs -F image $((16 * 1024*1024*1024))"
240 while ((kilobytes >> 22) >= blocksize)
245 if (blocksize < EXT2_MIN_BLOCK_SIZE
246 || blocksize > EXT2_MAX_BLOCK_SIZE
247 || (blocksize & (blocksize - 1)) // not power of 2
249 bb_error_msg_and_die("blocksize %u is bad", blocksize);
251 if ((int32_t)bytes_per_inode < blocksize)
252 bb_error_msg_and_die("-%c is bad", 'i');
253 // number of bits in one block, i.e. 8*blocksize
254 #define blocks_per_group (8 * blocksize)
255 first_block = (EXT2_MIN_BLOCK_SIZE == blocksize);
256 blocksize_log2 = int_log2(blocksize);
258 // Determine number of blocks
259 kilobytes >>= (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
261 if (nblocks != kilobytes)
262 bb_error_msg_and_die("block count doesn't fit in 32 bits");
263 #define kilobytes kilobytes_unused_after_this
265 // if (blocksize < PAGE_SIZE)
266 // nblocks &= ~((PAGE_SIZE >> blocksize_log2)-1);
267 // Experimentally, standard mke2fs won't work on images smaller than 60k
269 bb_error_msg_and_die("need >= 60 blocks");
271 // How many reserved blocks?
272 if (reserved_percent > 50)
273 bb_error_msg_and_die("-%c is bad", 'm');
274 nreserved = (uint64_t)nblocks * reserved_percent / 100;
276 // N.B. killing e2fsprogs feature! Unused blocks don't account in calculations
277 nblocks_full = nblocks;
279 // If last block group is too small, nblocks may be decreased in order
280 // to discard it, and control returns here to recalculate some
282 // Note: blocksize and bytes_per_inode are never recalculated.
284 // N.B. a block group can have no more than blocks_per_group blocks
285 ngroups = div_roundup(nblocks - first_block, blocks_per_group);
287 group_desc_blocks = div_roundup(ngroups, blocksize / sizeof(*gd));
288 // TODO: reserved blocks must be marked as such in the bitmaps,
289 // or resulting filesystem is corrupt
290 if (ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT) {
292 * From e2fsprogs: Calculate the number of GDT blocks to reserve for online
294 * The absolute maximum number of GDT blocks we can reserve is determined by
295 * the number of block pointers that can fit into a single block.
296 * We set it at 1024x the current filesystem size, or
297 * the upper block count limit (2^32), whichever is lower.
299 uint32_t reserved_group_desc_blocks = 0xFFFFFFFF; // maximum block number
300 if (nblocks < reserved_group_desc_blocks / 1024)
301 reserved_group_desc_blocks = nblocks * 1024;
302 reserved_group_desc_blocks = div_roundup(reserved_group_desc_blocks - first_block, blocks_per_group);
303 reserved_group_desc_blocks = div_roundup(reserved_group_desc_blocks, blocksize / sizeof(*gd)) - group_desc_blocks;
304 if (reserved_group_desc_blocks > blocksize / sizeof(uint32_t))
305 reserved_group_desc_blocks = blocksize / sizeof(uint32_t);
306 //TODO: STORE_LE(sb->s_reserved_gdt_blocks, reserved_group_desc_blocks);
307 group_desc_blocks += reserved_group_desc_blocks;
311 // N.B. e2fsprogs does as follows!
312 uint32_t overhead, remainder;
313 // ninodes is the max number of inodes in this filesystem
314 uint32_t ninodes = ((uint64_t) nblocks_full * blocksize) / bytes_per_inode;
315 if (ninodes < EXT2_GOOD_OLD_FIRST_INO+1)
316 ninodes = EXT2_GOOD_OLD_FIRST_INO+1;
317 inodes_per_group = div_roundup(ninodes, ngroups);
318 // minimum number because the first EXT2_GOOD_OLD_FIRST_INO-1 are reserved
319 if (inodes_per_group < 16)
320 inodes_per_group = 16;
321 // a block group can't have more inodes than blocks
322 if (inodes_per_group > blocks_per_group)
323 inodes_per_group = blocks_per_group;
324 // adjust inodes per group so they completely fill the inode table blocks in the descriptor
325 //incompatibility on images >= 0.5GB:
326 //difference in sizeof(*inode) sometimes
327 //results in slightly bigger inodes_per_group here
328 //compared to standard mke2fs:
329 inodes_per_group = (div_roundup(inodes_per_group * sizeof(*inode), blocksize) * blocksize) / sizeof(*inode);
330 // make sure the number of inodes per group is a multiple of 8
331 inodes_per_group &= ~7;
332 inode_table_blocks = div_roundup(inodes_per_group * sizeof(*inode), blocksize);
334 // to be useful, lost+found should occupy at least 2 blocks (but not exceeding 16*1024 bytes),
335 // and at most EXT2_NDIR_BLOCKS. So reserve these blocks right now
336 /* Or e2fsprogs comment verbatim (what does it mean?):
337 * Ensure that lost+found is at least 2 blocks, so we always
338 * test large empty blocks for big-block filesystems. */
339 lost_and_found_blocks = MIN(EXT2_NDIR_BLOCKS, 16 >> (blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE));
341 // the last group needs more attention: isn't it too small for possible overhead?
342 overhead = (has_super(ngroups - 1) ? (1/*sb*/ + group_desc_blocks) : 0) + 1/*bbmp*/ + 1/*ibmp*/ + inode_table_blocks;
343 remainder = (nblocks - first_block) % blocks_per_group;
344 ////can't happen, nblocks >= 60 guarantees this
345 ////if ((1 == ngroups)
347 //// && (remainder < overhead + 1/* "/" */ + lost_and_found_blocks)
349 //// bb_error_msg_and_die("way small device");
352 // Standard mke2fs uses 50. Looks like a bug in our calculation
353 // of "remainder" or "overhead" - we don't match standard mke2fs
354 // when we transition from one group to two groups
355 // (a bit after 8M image size), but it works for two->three groups
356 // transition (at 16M).
357 if (remainder && (remainder < overhead + 50)) {
358 //bb_info_msg("CHOP[%u]", remainder);
359 nblocks -= remainder;
364 if (nblocks_full - nblocks)
365 printf("warning: %u blocks unused\n\n", nblocks_full - nblocks);
367 "Filesystem label=%s\n"
369 "Block size=%u (log=%u)\n"
370 "Fragment size=%u (log=%u)\n"
371 "%u inodes, %u blocks\n"
372 "%u blocks (%u%%) reserved for the super user\n"
373 "First data block=%u\n"
374 "Maximum filesystem blocks=%u\n"
376 "%u blocks per group, %u fragments per group\n"
377 "%u inodes per group"
379 , blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
380 , blocksize, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE
381 , inodes_per_group * ngroups, nblocks
382 , nreserved, reserved_percent
384 , group_desc_blocks * (blocksize / sizeof(*gd)) * blocks_per_group
386 , blocks_per_group, blocks_per_group
390 const char *fmt = "\nSuperblock backups stored on blocks:\n"
393 for (i = 1; i < ngroups; i++) {
394 pos += blocks_per_group;
396 printf(fmt, (unsigned)pos);
404 if (ENABLE_FEATURE_CLEAN_UP)
409 // TODO: 3/5 refuse if mounted
410 // TODO: 4/5 compat options
411 // TODO: 1/5 sanity checks
412 // TODO: 0/5 more verbose error messages
413 // TODO: 4/5 bigendianness: recheck, wait for ARM reporters
414 // TODO: 2/5 reserved GDT: how to mark but not allocate?
415 // TODO: 3/5 dir_index?
417 // fill the superblock
419 STORE_LE(sb->s_rev_level, 1); // revision 1 filesystem
420 STORE_LE(sb->s_magic, EXT2_SUPER_MAGIC);
422 //on images > 0.5GB, standard mke2fs uses 256 byte inodes.
423 //we always use 128 byte ones:
424 STORE_LE(sb->s_inode_size, sizeof(*inode));
425 STORE_LE(sb->s_first_ino, EXT2_GOOD_OLD_FIRST_INO);
426 STORE_LE(sb->s_log_block_size, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
427 STORE_LE(sb->s_log_frag_size, blocksize_log2 - EXT2_MIN_BLOCK_LOG_SIZE);
428 // first 1024 bytes of the device are for boot record. If block size is 1024 bytes, then
429 // the first block is 1, otherwise 0
430 STORE_LE(sb->s_first_data_block, first_block);
431 // block and inode bitmaps occupy no more than one block, so maximum number of blocks is
432 STORE_LE(sb->s_blocks_per_group, blocks_per_group);
433 STORE_LE(sb->s_frags_per_group, blocks_per_group);
435 STORE_LE(sb->s_blocks_count, nblocks);
436 // reserve blocks for superuser
437 STORE_LE(sb->s_r_blocks_count, nreserved);
439 STORE_LE(sb->s_inodes_per_group, inodes_per_group);
440 STORE_LE(sb->s_inodes_count, inodes_per_group * ngroups);
441 STORE_LE(sb->s_free_inodes_count, inodes_per_group * ngroups - EXT2_GOOD_OLD_FIRST_INO);
443 timestamp = time(NULL);
444 STORE_LE(sb->s_mkfs_time, timestamp);
445 STORE_LE(sb->s_wtime, timestamp);
446 STORE_LE(sb->s_lastcheck, timestamp);
448 STORE_LE(sb->s_state, 1); // TODO: what's 1?
449 STORE_LE(sb->s_creator_os, EXT2_OS_LINUX);
450 STORE_LE(sb->s_checkinterval, 24*60*60 * 180); // 180 days
451 STORE_LE(sb->s_errors, EXT2_ERRORS_DEFAULT);
452 STORE_LE(sb->s_feature_compat, EXT2_FEATURE_COMPAT_SUPP
453 | (EXT2_FEATURE_COMPAT_RESIZE_INO * ENABLE_FEATURE_MKFS_EXT2_RESERVED_GDT)
454 | (EXT2_FEATURE_COMPAT_DIR_INDEX * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX)
456 // e2fsck from 1.41.9 doesn't like EXT2_FEATURE_INCOMPAT_WHITEOUT
457 STORE_LE(sb->s_feature_incompat, EXT2_FEATURE_INCOMPAT_FILETYPE);// | EXT2_FEATURE_INCOMPAT_WHITEOUT;
458 STORE_LE(sb->s_feature_ro_compat, EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER);
459 STORE_LE(sb->s_flags, EXT2_FLAGS_SIGNED_HASH * ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX);
460 generate_uuid(sb->s_uuid);
461 if (ENABLE_FEATURE_MKFS_EXT2_DIR_INDEX) {
462 STORE_LE(sb->s_def_hash_version, EXT2_HASH_HALF_MD4);
463 generate_uuid((uint8_t *)sb->s_hash_seed);
466 * From e2fsprogs: add "jitter" to the superblock's check interval so that we
467 * don't check all the filesystems at the same time. We use a
468 * kludgy hack of using the UUID to derive a random jitter value.
470 STORE_LE(sb->s_max_mnt_count,
471 EXT2_DFL_MAX_MNT_COUNT
472 + (sb->s_uuid[ARRAY_SIZE(sb->s_uuid)-1] % EXT2_DFL_MAX_MNT_COUNT));
475 safe_strncpy((char *)sb->s_volume_name, label, sizeof(sb->s_volume_name));
477 // calculate filesystem skeleton structures
478 gd = xzalloc(group_desc_blocks * blocksize);
479 buf = xmalloc(blocksize);
480 sb->s_free_blocks_count = 0;
481 for (i = 0, pos = first_block, n = nblocks - first_block;
483 i++, pos += blocks_per_group, n -= blocks_per_group
485 uint32_t overhead = pos + (has_super(i) ? (1/*sb*/ + group_desc_blocks) : 0);
486 uint32_t free_blocks;
487 // fill group descriptors
488 STORE_LE(gd[i].bg_block_bitmap, overhead + 0);
489 STORE_LE(gd[i].bg_inode_bitmap, overhead + 1);
490 STORE_LE(gd[i].bg_inode_table, overhead + 2);
491 overhead = overhead - pos + 1/*bbmp*/ + 1/*ibmp*/ + inode_table_blocks;
492 gd[i].bg_free_inodes_count = inodes_per_group;
493 //STORE_LE(gd[i].bg_used_dirs_count, 0);
494 // N.B. both "/" and "/lost+found" are within the first block group
495 // "/" occupies 1 block, "/lost+found" occupies lost_and_found_blocks...
497 // ... thus increased overhead for the first block group ...
498 overhead += 1 + lost_and_found_blocks;
499 // ... and 2 used directories
500 STORE_LE(gd[i].bg_used_dirs_count, 2);
501 // well known reserved inodes belong to the first block too
502 gd[i].bg_free_inodes_count -= EXT2_GOOD_OLD_FIRST_INO;
505 // cache free block count of the group
506 free_blocks = (n < blocks_per_group ? n : blocks_per_group) - overhead;
508 // mark preallocated blocks as allocated
509 //bb_info_msg("ALLOC: [%u][%u][%u]", blocksize, overhead, blocks_per_group - (free_blocks + overhead));
510 allocate(buf, blocksize,
511 // reserve "overhead" blocks
513 // mark unused trailing blocks
514 blocks_per_group - (free_blocks + overhead)
517 PUT((uint64_t)(FETCH_LE32(gd[i].bg_block_bitmap)) * blocksize, buf, blocksize);
518 STORE_LE(gd[i].bg_free_blocks_count, free_blocks);
520 // mark preallocated inodes as allocated
521 allocate(buf, blocksize,
522 // mark reserved inodes
523 inodes_per_group - gd[i].bg_free_inodes_count,
524 // mark unused trailing inodes
525 blocks_per_group - inodes_per_group
528 //PUT((uint64_t)(FETCH_LE32(gd[i].bg_block_bitmap)) * blocksize, buf, blocksize);
529 //but it's right after block bitmap, so we can just:
530 xwrite(fd, buf, blocksize);
531 STORE_LE(gd[i].bg_free_inodes_count, gd[i].bg_free_inodes_count);
533 // count overall free blocks
534 sb->s_free_blocks_count += free_blocks;
536 STORE_LE(sb->s_free_blocks_count, sb->s_free_blocks_count);
538 // dump filesystem skeleton structures
539 // printf("Writing superblocks and filesystem accounting information: ");
540 for (i = 0, pos = first_block; i < ngroups; i++, pos += blocks_per_group) {
541 // dump superblock and group descriptors and their backups
543 // N.B. 1024 byte blocks are special
544 PUT(((uint64_t)pos * blocksize) + ((0 == i && 1024 != blocksize) ? 1024 : 0),
546 PUT(((uint64_t)pos * blocksize) + blocksize,
547 gd, group_desc_blocks * blocksize);
552 memset(buf, 0, blocksize);
553 PUT(0, buf, 1024); // N.B. 1024 <= blocksize, so buf[0..1023] contains zeros
555 for (i = 0; i < ngroups; ++i)
556 for (n = 0; n < inode_table_blocks; ++n)
557 PUT((uint64_t)(FETCH_LE32(gd[i].bg_inode_table) + n) * blocksize,
560 // prepare directory inode
561 inode = (struct ext2_inode *)buf;
562 STORE_LE(inode->i_mode, S_IFDIR | S_IRWXU | S_IRGRP | S_IROTH | S_IXGRP | S_IXOTH);
563 STORE_LE(inode->i_mtime, timestamp);
564 STORE_LE(inode->i_atime, timestamp);
565 STORE_LE(inode->i_ctime, timestamp);
566 STORE_LE(inode->i_size, blocksize);
567 // inode->i_blocks stores the number of 512 byte data blocks
568 // (512, because it goes directly to struct stat without scaling)
569 STORE_LE(inode->i_blocks, blocksize / 512);
571 // dump root dir inode
572 STORE_LE(inode->i_links_count, 3); // "/.", "/..", "/lost+found/.." point to this inode
573 STORE_LE(inode->i_block[0], FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks);
574 PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_ROOT_INO-1) * sizeof(*inode),
575 buf, sizeof(*inode));
577 // dump lost+found dir inode
578 STORE_LE(inode->i_links_count, 2); // both "/lost+found" and "/lost+found/." point to this inode
579 STORE_LE(inode->i_size, lost_and_found_blocks * blocksize);
580 STORE_LE(inode->i_blocks, (lost_and_found_blocks * blocksize) / 512);
581 n = FETCH_LE32(inode->i_block[0]) + 1;
582 for (i = 0; i < lost_and_found_blocks; ++i)
583 STORE_LE(inode->i_block[i], i + n); // use next block
584 //bb_info_msg("LAST BLOCK USED[%u]", i + n);
585 PUT(((uint64_t)FETCH_LE32(gd[0].bg_inode_table) * blocksize) + (EXT2_GOOD_OLD_FIRST_INO-1) * sizeof(*inode),
586 buf, sizeof(*inode));
588 // zero the blocks for "/lost+found"
589 memset(buf, 0, blocksize);
590 for (i = 1; i < lost_and_found_blocks; ++i)
591 PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 1+i) * blocksize,
595 dir = (struct ext2_dir *)buf;
597 // dump lost+found dir block
598 STORE_LE(dir->inode1, EXT2_GOOD_OLD_FIRST_INO);
599 STORE_LE(dir->rec_len1, 12);
600 STORE_LE(dir->name_len1, 1);
601 STORE_LE(dir->file_type1, EXT2_FT_DIR);
603 STORE_LE(dir->inode2, EXT2_ROOT_INO);
604 STORE_LE(dir->rec_len2, blocksize - 12);
605 STORE_LE(dir->name_len2, 2);
606 STORE_LE(dir->file_type2, EXT2_FT_DIR);
607 dir->name2[0] = '.'; dir->name2[1] = '.';
608 PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 1) * blocksize, buf, blocksize);
610 // dump root dir block
611 STORE_LE(dir->inode1, EXT2_ROOT_INO);
612 STORE_LE(dir->rec_len2, 12);
613 STORE_LE(dir->inode3, EXT2_GOOD_OLD_FIRST_INO);
614 STORE_LE(dir->rec_len3, blocksize - 12 - 12);
615 STORE_LE(dir->name_len3, 10);
616 STORE_LE(dir->file_type3, EXT2_FT_DIR);
617 strcpy(dir->name3, "lost+found");
618 PUT((uint64_t)(FETCH_LE32(gd[0].bg_inode_table) + inode_table_blocks + 0) * blocksize, buf, blocksize);
621 if (ENABLE_FEATURE_CLEAN_UP) {