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@xxxxxxxxx>
---
fs/exfat/balloc.c | 47 +++++++++++++++++++--------------------------
fs/exfat/exfat_fs.h | 1 +
2 files changed, 21 insertions(+), 27 deletions(-)
diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
index e918decb3735..a7b3a234ba9b 100644
--- a/fs/exfat/balloc.c
+++ b/fs/exfat/balloc.c
@@ -5,11 +5,20 @@
#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 lel_to_cpu(A) le32_to_cpu(A)
+#elif BITS_PER_LONG == 64
+# 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 +35,6 @@ 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 +237,25 @@ 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_MASK;
+ 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);
+ clu_bits = lel_to_cpu(*bitmap);
+ count += hweight_long(clu_bits);
+ 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(*bitmap) & BITMAP_LAST_WORD_MASK(last_mask);
+ count += hweight_long(clu_bits);
}
*ret_count = count;
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index a7a2c35d74fb..1cb3bf1851c8 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -136,6 +136,7 @@ enum {
#define BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent) \
((ent / BITS_PER_BYTE) & ((sb)->s_blocksize - 1))
#define BITS_PER_BYTE_MASK 0x7
+#define BITS_PER_LONG_MASK (BITS_PER_LONG - 1)
#define IGNORED_BITS_REMAINED(clu, clu_base) ((1 << ((clu) - (clu_base))) - 1)
#define ES_ENTRY_NUM(name_len) (ES_IDX_LAST_FILENAME(name_len) + 1)
--
2.43.0
