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sbitmap: add sbitmap_find_bit to remove repeat code in __sbitmap_get/__sbitmap_get_shallow

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There are three differences between __sbitmap_get and
__sbitmap_get_shallow when searching free bit:
1. __sbitmap_get_shallow limit number of bit to search per word.
__sbitmap_get has no such limit.
2. __sbitmap_get_shallow always searches with wrap set. __sbitmap_get set
wrap according to round_robin.
3. __sbitmap_get_shallow always searches from first bit in first word.
__sbitmap_get searches from first bit when round_robin is not set
otherwise searches from SB_NR_TO_BIT(sb, alloc_hint).

Add helper function sbitmap_find_bit function to do common search while
accept "limit depth per word", "wrap flag" and "first bit to
search" from caller to support the need of both __sbitmap_get and
__sbitmap_get_shallow.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://lore.kernel.org/r/20230116205059.3821738-5-shikemeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Kemeng Shi 2023-01-17 04:50:58 +08:00 committed by Jens Axboe
parent 08470a98a7
commit 678418c612
1 changed files with 35 additions and 39 deletions
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74
lib/sbitmap.c
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@ -186,10 +186,39 @@ static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
return nr;
}
static int sbitmap_find_bit(struct sbitmap *sb,
unsigned int depth,
unsigned int index,
unsigned int alloc_hint,
bool wrap)
{
unsigned int i;
int nr = -1;
for (i = 0; i < sb->map_nr; i++) {
nr = sbitmap_find_bit_in_word(&sb->map[index],
min_t(unsigned int,
__map_depth(sb, index),
depth),
alloc_hint, wrap);
if (nr != -1) {
nr += index << sb->shift;
break;
}
/* Jump to next index. */
alloc_hint = 0;
if (++index >= sb->map_nr)
index = 0;
}
return nr;
}
static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
{
unsigned int i, index;
int nr = -1;
unsigned int index;
index = SB_NR_TO_INDEX(sb, alloc_hint);
@ -203,22 +232,8 @@ static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
else
alloc_hint = 0;
for (i = 0; i < sb->map_nr; i++) {
nr = sbitmap_find_bit_in_word(&sb->map[index],
__map_depth(sb, index),
alloc_hint, !sb->round_robin);
if (nr != -1) {
nr += index << sb->shift;
break;
}
/* Jump to next index. */
alloc_hint = 0;
if (++index >= sb->map_nr)
index = 0;
}
return nr;
return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint,
!sb->round_robin);
}
int sbitmap_get(struct sbitmap *sb)
@ -242,31 +257,12 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
unsigned int alloc_hint,
unsigned long shallow_depth)
{
unsigned int i, index;
int nr = -1;
unsigned int index;
index = SB_NR_TO_INDEX(sb, alloc_hint);
alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
for (i = 0; i < sb->map_nr; i++) {
nr = sbitmap_find_bit_in_word(&sb->map[index],
min_t(unsigned int,
__map_depth(sb, index),
shallow_depth),
alloc_hint, true);
if (nr != -1) {
nr += index << sb->shift;
break;
}
/* Jump to next index. */
alloc_hint = 0;
if (++index >= sb->map_nr)
index = 0;
}
return nr;
return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);
}
int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)