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exfat: using hweight instead of internal logic

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Replace the internal table lookup algorithm with the hweight
library, which has instruction set acceleration capabilities.

Use it to increase the length of a single calculation of
the exfat_find_free_bitmap function to the long type.

Signed-off-by: John Sanpe <sanpeqf@gmail.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
John Sanpe 2023-12-05 23:58:37 +08:00 committed by Namjae Jeon
parent 0dd3ee3112
commit 7423546040
1 changed files with 21 additions and 27 deletions
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48
fs/exfat/balloc.c
View file

@ -5,11 +5,22 @@
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/bitmap.h>
#include <linux/buffer_head.h>
#include "exfat_raw.h"
#include "exfat_fs.h"
#if BITS_PER_LONG == 32
#define __le_long __le32
#define lel_to_cpu(A) le32_to_cpu(A)
#elif BITS_PER_LONG == 64
#define __le_long __le64
#define lel_to_cpu(A) le64_to_cpu(A)
#else
#error "BITS_PER_LONG not 32 or 64"
#endif
static const unsigned char free_bit[] = {
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/* 0 ~ 19*/
0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~ 39*/
@ -26,22 +37,6 @@ static const unsigned char free_bit[] = {
0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0 /*240 ~ 254*/
};
static const unsigned char used_bit[] = {
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/* 0 ~ 19*/
2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~ 39*/
2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~ 59*/
4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~ 79*/
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~ 99*/
3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 /*240 ~ 255*/
};
/*
* Allocation Bitmap Management Functions
*/
@ -244,25 +239,24 @@ int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
unsigned int count = 0;
unsigned int i, map_i = 0, map_b = 0;
unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
unsigned char clu_bits;
const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
unsigned int last_mask = total_clus & (BITS_PER_LONG - 1);
unsigned long *bitmap, clu_bits;
total_clus &= ~last_mask;
for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
count += used_bit[clu_bits];
if (++map_b >= (unsigned int)sb->s_blocksize) {
for (i = 0; i < total_clus; i += BITS_PER_LONG) {
bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
count += hweight_long(*bitmap);
map_b += sizeof(long);
if (map_b >= (unsigned int)sb->s_blocksize) {
map_i++;
map_b = 0;
}
}
if (last_mask) {
clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
clu_bits &= last_bit_mask[last_mask];
count += used_bit[clu_bits];
bitmap = (void *)(sbi->vol_amap[map_i]->b_data + map_b);
clu_bits = lel_to_cpu(*(__le_long *)bitmap);
count += hweight_long(clu_bits & BITMAP_LAST_WORD_MASK(last_mask));
}
*ret_count = count;