From 34939ae005ec402ee183956114b1a74cb57b8b9d Mon Sep 17 00:00:00 2001 From: John Sanpe Date: Fri, 8 Dec 2023 07:47:01 +0800 Subject: 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: John Sanpe Acked-by: Sungjong Seo Signed-off-by: Namjae Jeon --- fs/exfat/balloc.c | 41 +++++++++++++++-------------------------- 1 file changed, 15 insertions(+), 26 deletions(-) (limited to 'fs/exfat/balloc.c') diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c index 3e3e9e4cce2f..0356c88252bd 100644 --- a/fs/exfat/balloc.c +++ b/fs/exfat/balloc.c @@ -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; -- cgit v1.2.3