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libext2fs: Implement ext2fs_find_first_zero_generic_bmap(). 

This function searches a bitmap for the first zero bit within a range.
It checks if there is a bitmap backend specific implementation
available (if the relevant field in bitmap_ops is non-NULL). If not,
it uses a generic and slow method by repeatedly calling test_bmap() in
a loop. Also change ext2fs_new_inode() to use this new function.

This change in itself does not result in a large speedup, rather it
refactors the code in preparation for the introduction of a faster
find_first_zero() for bitarray based bitmaps.

Signed-off-by: Sami Liedes <sami.liedes@iki.fi>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
bitmap-optimize
Sami Liedes 2012-03-10 22:36:12 +02:00 committed by Theodore Ts'o
parent 5f7c04972f
commit c1a1e7fc24
4 changed files with 100 additions and 20 deletions
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46
lib/ext2fs/alloc.c
View File

@ -106,10 +106,10 @@ errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
int mode EXT2FS_ATTR((unused)),
ext2fs_inode_bitmap map, ext2_ino_t *ret)
{
ext2_ino_t dir_group = 0;
ext2_ino_t i;
ext2_ino_t start_inode;
ext2_ino_t ino_in_group;
ext2_ino_t start_inode = 0;
ext2_ino_t i, ino_in_group, upto, first_zero;
errcode_t retval;
dgrp_t group;
EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
@ -118,31 +118,37 @@ errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
if (!map)
return EXT2_ET_NO_INODE_BITMAP;
if (dir > 0)
dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
if (dir > 0) {
group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
start_inode = (group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
}
if (start_inode < EXT2_FIRST_INODE(fs->super))
start_inode = EXT2_FIRST_INODE(fs->super);
if (start_inode > fs->super->s_inodes_count)
return EXT2_ET_INODE_ALLOC_FAIL;
i = start_inode;
ino_in_group = (i - 1) % EXT2_INODES_PER_GROUP(fs->super);
do {
if (ino_in_group == 0)
check_inode_uninit(fs, map, (i - 1) /
EXT2_INODES_PER_GROUP(fs->super));
ino_in_group = (i - 1) % EXT2_INODES_PER_GROUP(fs->super);
group = (i - 1) / EXT2_INODES_PER_GROUP(fs->super);
if (!ext2fs_fast_test_inode_bitmap2(map, i))
check_inode_uninit(fs, map, group);
upto = i + (EXT2_INODES_PER_GROUP(fs->super) - ino_in_group);
if (i < start_inode && upto >= start_inode)
upto = start_inode - 1;
if (upto > fs->super->s_inodes_count)
upto = fs->super->s_inodes_count;
retval = ext2fs_find_first_zero_inode_bitmap2(map, i, upto,
&first_zero);
if (retval == 0) {
i = first_zero;
break;
if (++ino_in_group == EXT2_INODES_PER_GROUP(fs->super))
ino_in_group = 0;
if (++i > fs->super->s_inodes_count) {
i = EXT2_FIRST_INODE(fs->super);
ino_in_group = ((i - 1) %
EXT2_INODES_PER_GROUP(fs->super));
}
if (retval != ENOENT)
return EXT2_ET_INODE_ALLOC_FAIL;
i = upto + 1;
if (i > fs->super->s_inodes_count)
i = EXT2_FIRST_INODE(fs->super);
} while (i != start_inode);
if (ext2fs_test_inode_bitmap2(map, i))

41
lib/ext2fs/bitops.h
View File

@ -152,6 +152,14 @@ extern void ext2fs_fast_unmark_inode_bitmap2(ext2fs_inode_bitmap bitmap,
ext2_ino_t inode);
extern int ext2fs_fast_test_inode_bitmap2(ext2fs_inode_bitmap bitmap,
ext2_ino_t inode);
extern errcode_t ext2fs_find_first_zero_block_bitmap2(ext2fs_block_bitmap bitmap,
ext2_ino_t start,
ext2_ino_t end,
ext2_ino_t *out);
extern errcode_t ext2fs_find_first_zero_inode_bitmap2(ext2fs_inode_bitmap bitmap,
ext2_ino_t start,
ext2_ino_t end,
ext2_ino_t *out);
extern blk64_t ext2fs_get_block_bitmap_start2(ext2fs_block_bitmap bitmap);
extern ext2_ino_t ext2fs_get_inode_bitmap_start2(ext2fs_inode_bitmap bitmap);
extern blk64_t ext2fs_get_block_bitmap_end2(ext2fs_block_bitmap bitmap);
@ -188,6 +196,9 @@ extern void ext2fs_mark_block_bitmap_range2(ext2fs_block_bitmap bitmap,
blk64_t block, unsigned int num);
extern void ext2fs_unmark_block_bitmap_range2(ext2fs_block_bitmap bitmap,
blk64_t block, unsigned int num);
extern errcode_t ext2fs_find_first_zero_generic_bmap(ext2fs_generic_bitmap bitmap,
__u64 start, __u64 end,
__u64 *out);
/*
* The inline routines themselves...
@ -593,6 +604,36 @@ _INLINE_ int ext2fs_fast_test_inode_bitmap2(ext2fs_inode_bitmap bitmap,
inode);
}
_INLINE_ errcode_t ext2fs_find_first_zero_block_bitmap2(ext2fs_block_bitmap bitmap,
ext2_ino_t start,
ext2_ino_t end,
ext2_ino_t *out)
{
__u64 o;
errcode_t rv;
rv = ext2fs_find_first_zero_generic_bmap((ext2fs_generic_bitmap) bitmap,
start, end, &o);
if (!rv)
*out = o;
return rv;
}
_INLINE_ errcode_t ext2fs_find_first_zero_inode_bitmap2(ext2fs_inode_bitmap bitmap,
ext2_ino_t start,
ext2_ino_t end,
ext2_ino_t *out)
{
__u64 o;
errcode_t rv;
rv = ext2fs_find_first_zero_generic_bmap((ext2fs_generic_bitmap) bitmap,
start, end, &o);
if (!rv)
*out = o;
return rv;
}
_INLINE_ blk64_t ext2fs_get_block_bitmap_start2(ext2fs_block_bitmap bitmap)
{
return ext2fs_get_generic_bmap_start((ext2fs_generic_bitmap) bitmap);

5
lib/ext2fs/bmap64.h
View File

@ -89,6 +89,11 @@ struct ext2_bitmap_ops {
__u64 start, size_t num, void *out);
void (*clear_bmap)(ext2fs_generic_bitmap bitmap);
void (*print_stats)(ext2fs_generic_bitmap);
/* Find the first zero bit between start and end, inclusive.
* May be NULL, in which case a generic function is used. */
errcode_t (*find_first_zero)(ext2fs_generic_bitmap bitmap,
__u64 start, __u64 end, __u64 *out);
};
extern struct ext2_bitmap_ops ext2fs_blkmap64_bitarray;

28
lib/ext2fs/gen_bitmap64.c
View File

@ -762,3 +762,31 @@ errcode_t ext2fs_convert_subcluster_bitmap(ext2_filsys fs,
*bitmap = cmap;
return 0;
}
errcode_t ext2fs_find_first_zero_generic_bmap(ext2fs_generic_bitmap bitmap,
__u64 start, __u64 end, __u64 *out)
{
int b;
if (bitmap->bitmap_ops->find_first_zero)
return bitmap->bitmap_ops->find_first_zero(bitmap, start, end, out);
if (!bitmap || !EXT2FS_IS_64_BITMAP(bitmap) || bitmap->cluster_bits)
return EINVAL;
if (start < bitmap->start || end > bitmap->end || start > end) {
warn_bitmap(bitmap, EXT2FS_TEST_ERROR, start);
return EINVAL;
}
while (start <= end) {
b = bitmap->bitmap_ops->test_bmap(bitmap, start);
if (!b) {
*out = start;
return 0;
}
start++;
}
return ENOENT;
}