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mkfs_ext2: shrink

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function                                             old     new   delta
has_super                                             28      25      -3
mkfs_ext2_main                                      2011    1980     -31

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2009-10-17 23:13:31 +02:00
parent 823b4e6f26
commit 4588775182
1 changed files with 11 additions and 8 deletions
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19
util-linux/mkfs_ext2.c
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@@ -95,14 +95,14 @@ static bool is_power_of(uint32_t x, uint16_t n)
return (z == (int)z); return (z == (int)z);
} }
static bool has_super(uint32_t x) static uint32_t has_super(uint32_t x)
{ {
return (0 == x || 1 == x || is_power_of(x, 3) || is_power_of(x, 5) || is_power_of(x, 7)); return (0 == x || 1 == x || is_power_of(x, 3) || is_power_of(x, 5) || is_power_of(x, 7));
} }
#else #else
static bool has_super(uint32_t x) static uint32_t has_super(uint32_t x)
{ {
static const uint32_t supers[] = { static const uint32_t supers[] = {
0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729, 0, 1, 3, 5, 7, 9, 25, 27, 49, 81, 125, 243, 343, 625, 729,
@@ -112,7 +112,8 @@ static bool has_super(uint32_t x)
48828125, 129140163, 244140625, 282475249, 387420489, 48828125, 129140163, 244140625, 282475249, 387420489,
1162261467, 1220703125, 1977326743, 3486784401/* >2^31 */, 1162261467, 1220703125, 1977326743, 3486784401/* >2^31 */,
}; };
for (int i = sizeof(supers)/sizeof(supers[0]); --i >= 0; ) unsigned i;
for (i = ARRAY_SIZE(supers); --i >= 0;)
if (x == supers[i]) if (x == supers[i])
return 1; return 1;
return 0; return 0;
@@ -358,7 +359,7 @@ int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
i < ngroups; i < ngroups;
i++, pos += nblocks_per_group, n -= nblocks_per_group i++, pos += nblocks_per_group, n -= nblocks_per_group
) { ) {
uint32_t overhead = pos + has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); uint32_t overhead = pos + (has_super(i) ? (1/*sb*/ + gdtsz + rgdtsz) : 0);
gd[i].bg_block_bitmap = overhead + 0; gd[i].bg_block_bitmap = overhead + 0;
gd[i].bg_inode_bitmap = overhead + 1; gd[i].bg_inode_bitmap = overhead + 1;
gd[i].bg_inode_table = overhead + 2; gd[i].bg_inode_table = overhead + 2;
@@ -384,19 +385,21 @@ int mkfs_ext2_main(int argc UNUSED_PARAM, char **argv)
// dump filesystem skeleton structures // dump filesystem skeleton structures
buf = xmalloc(blocksize); buf = xmalloc(blocksize);
for (i = 0, pos = first_data_block; i < ngroups; i++, pos += nblocks_per_group) { for (i = 0, pos = first_data_block; i < ngroups; i++, pos += nblocks_per_group) {
uint32_t overhead = has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); uint32_t overhead = has_super(i) ? (1/*sb*/ + gdtsz + rgdtsz) : 0;
uint32_t start;// = has_super(i) * (1/*sb*/ + gdtsz + rgdtsz); uint32_t start;// = has_super(i) ? (1/*sb*/ + gdtsz + rgdtsz) : 0;
uint32_t end; uint32_t end;
// dump superblock and group descriptors and their backups // dump superblock and group descriptors and their backups
if (overhead) { // N.B. in fact, we want (has_super(i)) condition, but it is equal to (overhead != 0) and is cheaper if (overhead) { // N.B. in fact, we want (has_super(i)) condition, but it is equal to (overhead != 0) and is cheaper
//bb_info_msg("SUPER@[%d]", pos); //bb_info_msg("SUPER@[%d]", pos);
// N.B. 1024 byte blocks are special // N.B. 1024 byte blocks are special
PUT(blocksize * pos + 1024 * (0 == i && 0 == first_data_block), sb, blocksize); PUT(blocksize * pos + ((0 == i && 0 == first_data_block) ? 1024 : 0), sb, blocksize);
PUT(blocksize * pos + blocksize, gd, (gdtsz + rgdtsz) * blocksize); PUT(blocksize * pos + blocksize, gd, (gdtsz + rgdtsz) * blocksize);
} }
start = overhead + 1/*bbmp*/ + 1/*ibmp*/ + itsz + (0 == i) * 2; // +2: /, /lost+found start = overhead + 1/*bbmp*/ + 1/*ibmp*/ + itsz;
if (i == 0)
start += 2; // for / and /lost+found
end = nblocks_per_group - (start + gd[i].bg_free_blocks_count); end = nblocks_per_group - (start + gd[i].bg_free_blocks_count);
// mark preallocated blocks as allocated // mark preallocated blocks as allocated
allocate(buf, blocksize, start, end); allocate(buf, blocksize, start, end);