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Recover automatic block number calculation #5

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Recover automatic block number calculation #5

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bfc28c7
Define {MAX_,}RESERVED_BLOCKS as floats
May 13, 2019
5b93731
Recover automatic block number calculation
May 13, 2019
d6e659d
Correct message for minimum block count
May 13, 2019
1b2a30e
Correct also commented code to take into account reserved blocks
May 13, 2019
944a4fd
Indirect blocks must be taken into account for stats
xOneca Jun 23, 2019
3e2fce1
Restore (MAX_)RESERVED_BLOCKS to integer division
xOneca Jul 5, 2020
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107 changes: 99 additions & 8 deletions genext2fs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,7 @@ static int blocksize = 1024;
#define SUPERBLOCK_SIZE 1024

#define BLOCKSIZE blocksize
#define ADDR_PER_BLOCK (BLOCKSIZE / sizeof(uint32))
#define BLOCKS_PER_GROUP 8192
#define INODES_PER_GROUP 8192
/* Percentage of blocks that are reserved.*/
Expand Down Expand Up @@ -2278,6 +2279,70 @@ add2fs_from_file(filesystem *fs, uint32 this_nod, FILE * fh, uint32 fs_timestamp
free(path2);
}

static long
calc_file_alloc_blocks(unsigned long size)
{
const int double_blocks = ADDR_PER_BLOCK * ADDR_PER_BLOCK;
long file_blocks = (size + BLOCKSIZE - 1) / BLOCKSIZE;
long final_file_blocks;

/* Total file data blocks:
* - direct blocks: EXT2_NDIR_BLOCKS
* - 1st indirect blocks: + ADDR_PER_BLOCK
* - 2nd indirect blocks: + ADDR_PER_BLOCK*ADDR_PER_BLOCK
* - 3rd indirect blocks: + ADDR_PER_BLOCK*ADDR_PER_BLOCK*ADDR_PER_BLOCK
*
* Total blocks allocated in disk:
* - direct blocks: EXT2_NDIR_BLOCKS
* - 1st indirect blocks: + (1 + ADDR_PER_BLOCK)
* - 2nd indirect blocks: + (1 + ADDR_PER_BLOCK + ADDR_PER_BLOCK*ADDR_PER_BLOCK)
* - 3rd indirect blocks: + (1 + ADDR_PER_BLOCK + ADDR_PER_BLOCK*ADDR_PER_BLOCK + ADDR_PER_BLOCK*ADDR_PER_BLOCK*ADDR_PER_BLOCK)
*/

if(file_blocks <= EXT2_NDIR_BLOCKS)
return file_blocks;

// All direct blocks used
file_blocks -= EXT2_NDIR_BLOCKS;
final_file_blocks = EXT2_NDIR_BLOCKS;

// Need 1st indirection
if(file_blocks <= ADDR_PER_BLOCK)
{
// +1 indirect block
final_file_blocks += 1 + file_blocks;
return final_file_blocks;
}

// All 1st indirect blocks used
file_blocks -= ADDR_PER_BLOCK;
final_file_blocks += 1 + ADDR_PER_BLOCK;

// Need 2nd indirection
if(file_blocks <= double_blocks)
{
int indirect_blocks = 1 + (file_blocks + ADDR_PER_BLOCK - 1) / ADDR_PER_BLOCK;
final_file_blocks += file_blocks + indirect_blocks;
return final_file_blocks;
}

// All 2nd indirect blocks used
file_blocks -= double_blocks;
final_file_blocks += 1 + double_blocks;

// Need 2rd indirection
if(file_blocks / double_blocks <= ADDR_PER_BLOCK)
{
//(1 + ADDR_PER_BLOCK + ADDR_PER_BLOCK*ADDR_PER_BLOCK + ADDR_PER_BLOCK*ADDR_PER_BLOCK*ADDR_PER_BLOCK)
int indirect_blocks = 1 + (file_blocks + double_blocks - 1) / double_blocks
+ (file_blocks + ADDR_PER_BLOCK - 1) / ADDR_PER_BLOCK;
final_file_blocks += file_blocks + indirect_blocks;
return final_file_blocks;
}

return -1;
}

// adds a tree of entries to the filesystem from current dir
static void
add2fs_from_dir(filesystem *fs, uint32 this_nod, int squash_uids, int squash_perms, uint32 fs_timestamp, struct stats *stats)
Expand Down Expand Up @@ -2318,8 +2383,14 @@ add2fs_from_dir(filesystem *fs, uint32 this_nod, int squash_uids, int squash_per
stats->ninodes++;
break;
case S_IFREG:
if((st.st_mode & S_IFMT) == S_IFREG || st.st_size > 4 * (EXT2_TIND_BLOCK+1))
stats->nblocks += (st.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
{
int total_blocks = calc_file_alloc_blocks(st.st_size);
if(total_blocks == -1)
error_msg_and_die("%s: file too large", dent->d_name);
stats->nblocks += total_blocks;
fprintf(stderr, "Large file: %lu final blocks\n", total_blocks);
// Fall through
}
case S_IFCHR:
case S_IFBLK:
case S_IFIFO:
Expand Down Expand Up @@ -3343,16 +3414,36 @@ main(int argc, char **argv)
}
else
{
if(reserved_frac == -1)
nbresrvd = nbblocks * RESERVED_BLOCKS;
else
nbresrvd = nbblocks * reserved_frac;

stats.ninodes = EXT2_FIRST_INO - 1 + (nbresrvd ? 1 : 0);
stats.ninodes = 0;
stats.nblocks = 0;

populate_fs(NULL, dopt, didx, squash_uids, squash_perms, fs_timestamp, &stats);

if(reserved_frac == -1)
reserved_frac = 1.0 * RESERVED_BLOCKS;

if(nbblocks == -1)
{
/* On filesystems with 1k block size, the bootloader area uses a full
* block. For 2048 and up, the superblock can be fitted into block 0.
*/
int first_block = (BLOCKSIZE == 1024);
/* bootloader block + superblock + data blocks */
nbblocks = 1 + first_block + stats.nblocks;
nbblocks += nbblocks * reserved_frac;
}
else
if(stats.nblocks > nbblocks)
{
unsigned long minimum_blocks = stats.nblocks + stats.nblocks * reserved_frac;
// fprintf(stderr, "number of blocks too low, increasing to %ld\n", minimum_blocks);
// nbblocks = minimum_blocks;
error_msg_and_die("number of blocks too low. Need at least %lu.", minimum_blocks);
}

nbresrvd = nbblocks * reserved_frac;
stats.ninodes += EXT2_FIRST_INO - 1 + (nbresrvd ? 1 : 0);

if(nbinodes == -1)
nbinodes = stats.ninodes;
else
Expand Down