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Commit 2a0d7a84 authored by John Sanpe's avatar John Sanpe Committed by Namjae Jeon
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exfat: using hweight instead of internal logic 



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: default avatarJohn Sanpe <sanpeqf@gmail.com>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
parent 3ad14904

balloc.c

+21 −27
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/version.h>

#include <linux/blkdev.h>

#include <linux/slab.h>

#include <linux/bitmap.h>

#include <linux/buffer_head.h>

#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)

#include <linux/sched/signal.h>
@@ -17,6 +18,16 @@ 
#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*/
@@ -33,22 +44,6 @@ 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

 */
@@ -255,25 +250,24 @@ 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;