1 /* 2 * linux/fs/ext4/bitmap.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 */ 9 10 #include <linux/buffer_head.h> 11 #include <linux/jbd2.h> 12 #include "ext4.h" 13 14 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0}; 15 16 unsigned int ext4_count_free(char *bitmap, unsigned int numchars) 17 { 18 unsigned int i, sum = 0; 19 20 for (i = 0; i < numchars; i++) 21 sum += nibblemap[bitmap[i] & 0xf] + 22 nibblemap[(bitmap[i] >> 4) & 0xf]; 23 return sum; 24 } 25 26 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, 27 struct ext4_group_desc *gdp, 28 struct buffer_head *bh, int sz) 29 { 30 __u32 hi; 31 __u32 provided, calculated; 32 struct ext4_sb_info *sbi = EXT4_SB(sb); 33 34 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 35 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 36 return 1; 37 38 provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo); 39 calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 40 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) { 41 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi); 42 provided |= (hi << 16); 43 } else 44 calculated &= 0xFFFF; 45 46 return provided == calculated; 47 } 48 49 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group, 50 struct ext4_group_desc *gdp, 51 struct buffer_head *bh, int sz) 52 { 53 __u32 csum; 54 struct ext4_sb_info *sbi = EXT4_SB(sb); 55 56 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 57 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 58 return; 59 60 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 61 gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF); 62 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) 63 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16); 64 } 65 66 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group, 67 struct ext4_group_desc *gdp, 68 struct buffer_head *bh, int sz) 69 { 70 __u32 hi; 71 __u32 provided, calculated; 72 struct ext4_sb_info *sbi = EXT4_SB(sb); 73 74 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 75 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 76 return 1; 77 78 provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo); 79 calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 80 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) { 81 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi); 82 provided |= (hi << 16); 83 } else 84 calculated &= 0xFFFF; 85 86 if (provided == calculated) 87 return 1; 88 89 ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group); 90 return 0; 91 } 92 93 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group, 94 struct ext4_group_desc *gdp, 95 struct buffer_head *bh, int sz) 96 { 97 __u32 csum; 98 struct ext4_sb_info *sbi = EXT4_SB(sb); 99 100 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 101 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) 102 return; 103 104 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz); 105 gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF); 106 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) 107 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16); 108 } 109