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* grub-core/fs/ext2.c (grub_ext2_read_block): Factor out common code for indirect block handling.

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Saves 185 bytes on compressed image.
This commit is contained in:
Colin Watson 2013-11-14 08:13:06 +00:00
parent e6050a683c
commit 5da5517288
2 changed files with 44 additions and 80 deletions
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7
ChangeLog
View file

@ -1,3 +1,10 @@
2013-11-14 Colin Watson <cjwatson@ubuntu.com>
* grub-core/fs/ext2.c (grub_ext2_read_block): Factor out common
code for indirect block handling.
Saves 185 bytes on compressed image.
2013-11-13 Paulo Flabiano Smorigo <pfsmorigo@br.ibm.com>
Fix make clean.

117
grub-core/fs/ext2.c
View file

@ -397,9 +397,12 @@ grub_ext2_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
{
struct grub_ext2_data *data = node->data;
struct grub_ext2_inode *inode = &node->inode;
grub_disk_addr_t blknr = -1;
unsigned int blksz = EXT2_BLOCK_SIZE (data);
grub_disk_addr_t blksz_quarter = blksz / 4;
int log2_blksz = LOG2_EXT2_BLOCK_SIZE (data);
int log_perblock = log2_blksz + 9 - 2;
grub_uint32_t indir;
int shift;
if (inode->flags & grub_cpu_to_le32_compile_time (EXT4_EXTENTS_FLAG))
{
@ -448,96 +451,50 @@ grub_ext2_read_block (grub_fshelp_node_t node, grub_disk_addr_t fileblock)
return ret;
}
/* Direct blocks. */
if (fileblock < INDIRECT_BLOCKS)
blknr = grub_le_to_cpu32 (inode->blocks.dir_blocks[fileblock]);
return grub_le_to_cpu32 (inode->blocks.dir_blocks[fileblock]);
fileblock -= INDIRECT_BLOCKS;
/* Indirect. */
else if (fileblock < INDIRECT_BLOCKS + blksz / 4)
if (fileblock < blksz_quarter)
{
grub_uint32_t indir;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (inode->blocks.indir_block))
<< log2_blksz,
(fileblock - INDIRECT_BLOCKS) * sizeof (indir),
sizeof (indir), &indir))
return grub_errno;
blknr = grub_le_to_cpu32 (indir);
indir = inode->blocks.indir_block;
shift = 0;
goto indirect;
}
fileblock -= blksz_quarter;
/* Double indirect. */
else if (fileblock < INDIRECT_BLOCKS
+ blksz / 4 * ((grub_disk_addr_t) blksz / 4 + 1))
if (fileblock < blksz_quarter * blksz_quarter)
{
int log_perblock = log2_blksz + 9 - 2;
grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS
+ blksz / 4);
grub_uint32_t indir;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (inode->blocks.double_indir_block))
<< log2_blksz,
(rblock >> log_perblock) * sizeof (indir),
sizeof (indir), &indir))
return grub_errno;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (indir))
<< log2_blksz,
(rblock & ((1 << log_perblock) - 1)) * sizeof (indir),
sizeof (indir), &indir))
return grub_errno;
blknr = grub_le_to_cpu32 (indir);
indir = inode->blocks.double_indir_block;
shift = 1;
goto indirect;
}
/* triple indirect. */
else if (fileblock < INDIRECT_BLOCKS + blksz / 4 * ((grub_disk_addr_t) blksz / 4 + 1)
+ ((grub_disk_addr_t) blksz / 4) * ((grub_disk_addr_t) blksz / 4)
* ((grub_disk_addr_t) blksz / 4 + 1))
fileblock -= blksz_quarter * blksz_quarter;
/* Triple indirect. */
if (fileblock < blksz_quarter * blksz_quarter * (blksz_quarter + 1))
{
int log_perblock = log2_blksz + 9 - 2;
grub_disk_addr_t rblock = fileblock - (INDIRECT_BLOCKS + blksz / 4
* (blksz / 4 + 1));
grub_uint32_t indir;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (inode->blocks.triple_indir_block))
<< log2_blksz,
((rblock >> log_perblock) >> log_perblock)
* sizeof (indir), sizeof (indir), &indir))
return grub_errno;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (indir))
<< log2_blksz,
((rblock >> log_perblock)
& ((1 << log_perblock) - 1)) * sizeof (indir),
sizeof (indir), &indir))
return grub_errno;
if (grub_disk_read (data->disk,
((grub_disk_addr_t)
grub_le_to_cpu32 (indir))
<< log2_blksz,
(rblock & ((1 << log_perblock) - 1))
* sizeof (indir), sizeof (indir), &indir))
return grub_errno;
blknr = grub_le_to_cpu32 (indir);
}
else
{
grub_error (GRUB_ERR_BAD_FS,
"ext2fs doesn't support quadruple indirect blocks");
indir = inode->blocks.triple_indir_block;
shift = 2;
goto indirect;
}
return grub_error (GRUB_ERR_BAD_FS,
"ext2fs doesn't support quadruple indirect blocks");
return blknr;
indirect:
do {
if (grub_disk_read (data->disk,
((grub_disk_addr_t) grub_le_to_cpu32 (indir))
<< log2_blksz,
((fileblock >> (log_perblock * shift))
& ((1 << log_perblock) - 1))
* sizeof (indir),
sizeof (indir), &indir))
return grub_errno;
} while (shift--);
return grub_le_to_cpu32 (indir);
}
/* Read LEN bytes from the file described by DATA starting with byte