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libext2fs: optimize ext2fs_new_block2() 

If there are hundreds of thousands of blocks which are in use before
the first free block, it is much, MUCH faster to use
ext2fs_find_first_zero_block_bitmap2() instead of searching the
allocation bitmap bit by bit.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
maint-test
Theodore Ts'o 2014-01-19 19:35:33 -05:00
parent fccdbac394
commit 424de6e8e3
1 changed files with 17 additions and 17 deletions
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34
lib/ext2fs/alloc.c
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@ -137,8 +137,8 @@ errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
errcode_t ext2fs_new_block2(ext2_filsys fs, blk64_t goal,
ext2fs_block_bitmap map, blk64_t *ret)
{
blk64_t i;
int c_ratio;
errcode_t retval;
blk64_t b;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
@ -148,21 +148,21 @@ errcode_t ext2fs_new_block2(ext2_filsys fs, blk64_t goal,
return EXT2_ET_NO_BLOCK_BITMAP;
if (!goal || (goal >= ext2fs_blocks_count(fs->super)))
goal = fs->super->s_first_data_block;
i = goal;
c_ratio = 1 << ext2fs_get_bitmap_granularity(map);
if (c_ratio > 1)
goal &= ~EXT2FS_CLUSTER_MASK(fs);
do {
if (!ext2fs_fast_test_block_bitmap2(map, i)) {
clear_block_uninit(fs, ext2fs_group_of_blk2(fs, i));
*ret = i;
return 0;
}
i = (i + c_ratio) & ~(c_ratio - 1);
if (i >= ext2fs_blocks_count(fs->super))
i = fs->super->s_first_data_block;
} while (i != goal);
return EXT2_ET_BLOCK_ALLOC_FAIL;
goal &= ~EXT2FS_CLUSTER_MASK(fs);
retval = ext2fs_find_first_zero_block_bitmap2(map,
goal, ext2fs_blocks_count(fs->super) - 1, &b);
if ((retval == ENOENT) && (goal != fs->super->s_first_data_block))
retval = ext2fs_find_first_zero_block_bitmap2(map,
fs->super->s_first_data_block, goal - 1, &b);
if (retval == ENOENT)
return EXT2_ET_BLOCK_ALLOC_FAIL;
if (retval)
return retval;
clear_block_uninit(fs, ext2fs_group_of_blk2(fs, b));
*ret = b;
return 0;
}
errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,