Commit 34939ae0 authored by John Sanpe's avatar John Sanpe Committed by Namjae Jeon
Browse files

exfat: using ffs instead of internal logic 



Replaced the internal table lookup algorithm with ffs of
the bitops library with better performance.

Use it to increase the single processing length of the
exfat_find_free_bitmap function, from single-byte search to long type.

Signed-off-by: default avatarJohn Sanpe <sanpeqf@gmail.com>
Acked-by: default avatarSungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
parent 74235460

fs/exfat/balloc.c

+15 −26
Original line number Diff line number Diff line
@@ -14,29 +14,15 @@ 
#if BITS_PER_LONG == 32

#define __le_long __le32

#define lel_to_cpu(A) le32_to_cpu(A)

#define cpu_to_lel(A) cpu_to_le32(A)

#elif BITS_PER_LONG == 64

#define __le_long __le64

#define lel_to_cpu(A) le64_to_cpu(A)

#define cpu_to_lel(A) cpu_to_le64(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*/

	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~  59*/

	0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~  79*/

	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~  99*/

	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/

	0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/

	0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/

	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/

	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/

	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/

	0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/

	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0                /*240 ~ 254*/

};



/*

 *  Allocation Bitmap Management Functions

 */
@@ -195,32 +181,35 @@ unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu) 
{

	unsigned int i, map_i, map_b, ent_idx;

	unsigned int clu_base, clu_free;

	unsigned char k, clu_mask;

	unsigned long clu_bits, clu_mask;

	struct exfat_sb_info *sbi = EXFAT_SB(sb);

	__le_long bitval;



	WARN_ON(clu < EXFAT_FIRST_CLUSTER);

	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);

	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));

	ent_idx = ALIGN_DOWN(CLUSTER_TO_BITMAP_ENT(clu), BITS_PER_LONG);

	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx);

	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);



	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);

	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);



	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;

	     i += BITS_PER_BYTE) {

		k = *(sbi->vol_amap[map_i]->b_data + map_b);

	     i += BITS_PER_LONG) {

		bitval = *(__le_long *)(sbi->vol_amap[map_i]->b_data + map_b);

		if (clu_mask > 0) {

			k |= clu_mask;

			bitval |= cpu_to_lel(clu_mask);

			clu_mask = 0;

		}

		if (k < 0xFF) {

			clu_free = clu_base + free_bit[k];

		if (lel_to_cpu(bitval) != ULONG_MAX) {

			clu_bits = lel_to_cpu(bitval);

			clu_free = clu_base + ffz(clu_bits);

			if (clu_free < sbi->num_clusters)

				return clu_free;

		}

		clu_base += BITS_PER_BYTE;

		clu_base += BITS_PER_LONG;

		map_b += sizeof(long);



		if (++map_b >= sb->s_blocksize ||

		if (map_b >= sb->s_blocksize ||

		    clu_base >= sbi->num_clusters) {

			if (++map_i >= sbi->map_sectors) {

				clu_base = EXFAT_FIRST_CLUSTER;

fs/exfat/exfat_fs.h

+1 −2
Original line number Diff line number Diff line
@@ -135,8 +135,7 @@ enum { 
#define BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent) (ent & BITS_PER_SECTOR_MASK(sb))

#define BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent) \

	((ent / BITS_PER_BYTE) & ((sb)->s_blocksize - 1))

#define BITS_PER_BYTE_MASK	0x7

#define IGNORED_BITS_REMAINED(clu, clu_base) ((1 << ((clu) - (clu_base))) - 1)

#define IGNORED_BITS_REMAINED(clu, clu_base) ((1UL << ((clu) - (clu_base))) - 1)



#define ES_ENTRY_NUM(name_len)	(ES_IDX_LAST_FILENAME(name_len) + 1)

/* 19 entries = 1 file entry + 1 stream entry + 17 filename entries */